Abstract: Advances in our understanding of cancer biology and discoveries emerging from cancer genomics are being translated into real clinical benefits for patients with cancer. The 2011 Journal of Pathology Annual Review Issue provides a snapshot of recent rapid progress on multiple fronts in the war on cancer or, more precisely, the wars on cancers. Indeed, perhaps the most notable recent shift is reflected by the sharp increase in understanding the biology of multiple specific cancers and using these new insights to inform rationally targeted therapies, with often striking successes. These recent developments, as reviewed in this issue, show how the long-term investments in basic cancer research are finally beginning to bear fruit.
Abstract: The histopathological diagnosis of gastrointestinal stromal tumours (GIST) is typically made based on a combination of clinical and morphological features supported by immunohistochemistry studies. The aim of this study was to examine the staining quality, sensitivity, specificity and utility of antibodies used commonly in GIST diagnosis.
Abstract: Chondromyxoid fibroma (CMF) is an uncommon benign cartilaginous tumor of bone usually occurring during the second decade of life. CMF is associated with recurrent rearrangements of chromosome bands 6p23-25, 6q12-15, and 6q23-27. To delineate further the role and frequency of the involvement of three candidate regions (6q13, 6q23.3 and 6q24) in the pathogenesis of CMF, we studied a group of 43 cases using a molecular cytogenetic approach. Fluorescence in situ hybridization with probe sets bracketing the putative breakpoint regions was performed in 30 cases. The expression level of nearby candidate genes was studied by immunohistochemistry and quantitative RT-PCR in 24 and 23 cases, respectively. Whole-genome copy number screening was performed by array comparative genomic hybridization in 16 cases. Balanced and unbalanced rearrangements of 6q13 and 6q23.3 occurred in six and five cases, respectively, and a hemizygous deletion in 6q24 was found in five cases. Two known tumor suppressor genes map to the latter region: PLAGL1 and UTRN. However, neither of these two genes nor BCLAF1 and COL12A1, respectively located in 6q23.3 and 6q13, showed altered expression. Therefore, although rearrangements of chromosomal regions 6q13, 6q23.3, and 6q24 are common in CMF, the complexity of the changes precludes the use of a single fluorescence in situ hybridization probe set as an adjunct diagnostic tool. These data indicate that the genetic alterations in CMF are heterogeneous and are likely a result of a cryptic rearrangement beyond the resolution level of combined binary ratio fluorescence in situ hybridization or a point mutation.
Abstract: Intimal sarcoma (IS) is a rare, malignant, and aggressive tumor that shows a relentless course with a concomitant low survival rate and for which no effective treatment is available. In this study, 21 cases of large arterial blood vessel IS were analyzed by immunohistochemistry and fluorescence in situ hybridization and selectively by karyotyping, array comparative genomic hybridization, sequencing, phospho-kinase antibody arrays, and Western immunoblotting in search for novel diagnostic markers and potential molecular therapeutic targets. Ex vivo immunoassays were applied to test the sensitivity of IS primary tumor cells to the receptor tyrosine kinase (RTK) inhibitors imatinib and dasatinib. We showed that amplification of platelet-derived growth factor receptor α (PDGFRA) is a common finding in IS, which should be considered as a molecular hallmark of this entity. This amplification is consistently associated with PDGFRA activation. Furthermore, the tumors reveal persistent activation of the epidermal growth factor receptor (EGFR), concurrent to PDGFRA activation. Activated PDGFRA and EGFR frequently coexist with amplification and overexpression of the MDM2 oncogene. Ex vivo immunoassays on primary IS cells from one case showed the potency of dasatinib to inhibit PDGFRA and downstream signaling pathways. Our findings provide a rationale for investigating therapies that target PDGFRA, EGFR, or MDM2 in IS. Given the clonal heterogeneity of this tumor type and the potential cross-talk between the PDGFRA and EGFR signaling pathways, targeting multiple RTKs and aberrant downstream effectors might be required to improve the therapeutic outcome for patients with this disease.
Abstract: Hemangiopericytoma (HPC) was first described as a neoplasm with distinct morphologic features, presumably composed of pericytes. In soft tissue, it is accepted that most such lesions are solitary fibrous tumors (SFTs), monophasic synovial sarcomas (SSs), or myofibromatoses. It is unclear whether HPC of bone exists. We reviewed 9 primary "HPC" of bone from 4 institutions diagnosed between 1952 and 2002. Immunohistochemistry was performed for CD31, CD34, von Willebrand factor, smooth muscle actin, keratin AE1/AE3, and epithelial membrane antigen. There were 4 male and 5 female patients between 21 and 73 years. All tumors were located within bone, either sited within spine or extremities. All tumors showed thin-walled branching vessels surrounded by undifferentiated spindle or round cells. These cells showed variation in their morphologic pattern: 6 tumors showed a pattern-less architecture and varying cellularity, consistent with SFT; 3 of 5 cases examined were CD34-positive. Three tumors showed more densely packed sheets and fascicles of poorly differentiated cells, resembling SS, of which 2 showed focal staining for keratin AE1/AE3 or epithelial membrane antigen. Fluorescent in-situ hybridization confirmed the presence of SS18 rearrangement in 1 of 2 tumors examined. In conclusion, similar to their soft-tissue counterpart, HPC-like features in bone are a nonspecific growth pattern rather than a true diagnosis. We confirm the existence of 2 entities: SFT and SS of bone. Both are characterized by distinct morphology and immunohistochemical profile. SFT of bone is located within spine and has a better prognosis, whereas SS of bone is located within long bones having a poor prognosis.
Abstract: Primary cilia are specialized cell surface projections found on most cell types. Involved in several signaling pathways, primary cilia have been reported to modulate cell and tissue organization. Although they have been implicated in regulating cartilage and bone growth, little is known about the organization of primary cilia in the growth plate cartilage and osteochondroma. Osteochondromas are bone tumors formed along the growth plate, and they are caused by mutations in EXT1 or EXT2 genes. In this study, we show the organization of primary cilia within and between the zones of the growth plate and osteochondroma. Using confocal and electron microscopy, we found that in both tissues, primary cilia have a similar formation but a distinct organization. The shortest ciliary length is associated with the proliferative state of the cells, as confirmed by Ki-67 immunostaining. Primary cilia organization in the growth plate showed that non-polarized chondrocytes (resting zone) are becoming polarized (proliferating and hypertrophic zones), orienting the primary cilia parallel to the longitudinal axis of the bone. The alignment of primary cilia forms one virtual axis that crosses the center of the columns of chondrocytes reflecting the polarity axis of the growth plate. We also show that primary cilia in osteochondromas are found randomly located on the cell surface. Strikingly, the growth plate-like polarity was retained in sub-populations of osteochondroma cells that were organized into small columns. Based on this, we propose the existence of a mixture ('mosaic') of normal lining (EXT(+/-) or EXT(wt/wt)) and EXT(-/-) cells in the cartilaginous cap of osteochondromas.
Abstract: The molecular mechanisms underlying the progression of central chondrosarcoma are so far poorly understood. The aim of this study was to identify genes involved in the progression of these tumours by comparison of gene expression and correlation of expression profiles to histological grade and clinical outcome.
Abstract: We have investigated the use of hierarchical clustering of flow cytometry data to classify samples of conventional central chondrosarcoma, a malignant cartilage forming tumor of uncertain cellular origin, according to similarities with surface marker profiles of several known cell types. Human primary chondrosarcoma cells, articular chondrocytes, mesenchymal stem cells, fibroblasts, and a panel of tumor cell lines from chondrocytic or epithelial origin were clustered based on the expression profile of eleven surface markers. For clustering, eight hierarchical clustering algorithms, three distance metrics, as well as several approaches for data preprocessing, including multivariate outlier detection, logarithmic transformation, and z-score normalization, were systematically evaluated. By selecting clustering approaches shown to give reproducible results for cluster recovery of known cell types, primary conventional central chondrosacoma cells could be grouped in two main clusters with distinctive marker expression signatures: one group clustering together with mesenchymal stem cells (CD49b-high/CD10-low/CD221-high) and a second group clustering close to fibroblasts (CD49b-low/CD10-high/CD221-low). Hierarchical clustering also revealed substantial differences between primary conventional central chondrosarcoma cells and established chondrosarcoma cell lines, with the latter not only segregating apart from primary tumor cells and normal tissue cells, but clustering together with cell lines from epithelial lineage. Our study provides a foundation for the use of hierarchical clustering applied to flow cytometry data as a powerful tool to classify samples according to marker expression patterns, which could lead to uncover new cancer subtypes.
Abstract: As a group, cartilage tumours are the most common primary bone lesions. They range from benign lesions, such as enchondromas and osteochondromas, to malignant chondrosarcoma. The benign lesions result from the deregulation of the hedgehog signalling pathway, which is involved in normal bone development. These lesions can be the precursors of malignant chondrosarcomas, which are notoriously resistant to conventional chemotherapy and radiotherapy. Cytogenetic studies and mouse models are beginning to identify genes and signalling pathways that have roles in tumour progression, such as hedgehog, p53, insulin-like growth factor, cyclin-dependent kinase 4, hypoxia-inducible factor, matrix metalloproteinases, SRC and AKT, suggesting potential new therapeutic approaches.
Abstract: Myxofibrosarcoma and myxoid liposarcomas are relatively common soft tissue tumours that are characterized by their so-called myxoid extracellular matrix and have to some extent overlap in histology. The exact composition and potential role of their myxoid extracellular matrix are insufficiently understood. To gain more insight into the biomolecular content of these tumours, we have studied 40 well-documented myxofibrosarcoma and myxoid liposarcoma cases using imaging mass spectrometry. This technique provides a multiplex biomolecular imaging analysis of the tissue, spanning multiple molecular domains and without a priori knowledge of the tissue's biomolecular content. We have developed experimental protocols for analysing the peptide, protein, and lipid content of myxofibrosarcoma and myxoid liposarcomas, and have detected proteins and lipids that are tumour-type and tumour-grade specific. In particular, lipid changes observed in myxoid liposarcomas could be related to pathways known to be affected during tumour progression. Unsupervised clustering of the biomolecular signatures was able to classify myxofibrosarcoma and myxoid liposarcomas according to tumour type and tumour grade. Closer examination of histologically similar regions in the tissues revealed intratumour heterogeneity, which was a consistent feature in each of the myxofibrosarcomas studied. In intermediate-grade myxofibrosarcoma, it was found that single tissue sections could contain regions with biomolecular profiles similar to high-grade and low-grade tumours, and that these regions were associated with the tumour's nodular structure, thus supporting a concept of tumour progression through clonal selection.
Abstract: Desmoid-type fibromatoses are neoplasms of fibroblastic origin, occurring sporadically or associated with familial adenomatous polyposis (FAP) coli. By comparing sporadic and FAP-associated desmoid-type fibromatoses, we tried to identify clinical characteristics, which may indicate FAP. Histopathology data of all Dutch patients with desmoid-type fibromatoses diagnosed between 1999 and 2009 were retrieved from PALGA, the nation-wide network and registry of histopathology in the Netherlands. For calculation of incidence rates, person-years from the general matched population were used. Based on polyp counts in pathological records, the cohort was divided into a FAP group and a non-FAP group. Patient- and tumor characteristics were compared between the two groups. A total number of 519 patients older than 10 years with a confirmed diagnosis of desmoid-type fibromatoses were included. Thirty-nine (7.5%) desmoid patients were documented of having FAP. The incidences of sporadic and FAP-related desmoid-type fibromatoses were 3.42 and 2,784 per million person-years, respectively. The majority of FAP patients developed desmoid-type fibromatoses after the diagnosis of FAP. Having FAP was associated with male gender [odds ratio (OR) 2.0, p = 0.034], desmoid diagnosis at an earlier age (mean 36 vs. 42 years, p = 0.031), and desmoid localization intra-abdominally (OR 18.9, p ≤ 0.001) or in the abdominal wall (OR 4.8, p ≤ 0.001), compared to extra-abdominal desmoid localization. In conclusion, patients with desmoid-type fibromatoses are at risk of underlying FAP. Especially cases with desmoid localization intra-abdominal or in the abdominal wall, and all patients younger than 60 years, have a substantial increased risk and should be referred for colonoscopy.
Abstract: BACKGROUND AND AIM: Rarely sarcomas develop in previous benign lesions, after a long term disease free interval. We report the experience on these rare cases observed at a single Institution. PATIENTS AND METHODS: 12 cases curetted and grafted, without radiotherapy developed sarcomas, between 1970 and 2005, 6.5-28 years from curettage (median 18, average 19). Age ranged from 13 to 55 years (median 30, average 32) at first diagnosis; tumors were located in the extremities (9 GCT, benign fibrous histiocytoma, ABC, and solitary bone cyst). Radiographic and clinic documentation, for the benign and malignant lesions, were available. Histology was available for 7 benign and all malignant lesions. RESULTS: To fill cavities, autogenous bone was used in 4 cases, allograft in 2, allograft and tricalcium-phosphate/hydroxyapatite in 1, autogenous/allograft in 1, heterogenous in 1. For 3 cases the origin was not reported. Secondary sarcomas, all high grade, were 8 osteosarcoma, 3 malignant fibrous histiocytoma, and 1 fibrosarcoma. CONCLUSIONS: Recurrences with progression from benign tumors are possible, but the very long intervals here reported suggest a different cancerogenesis for these sarcomas. This condition is extremely rare accounting for only 0.26% of all malignant bone sarcomas treated in the years 1970-2005 and represents only 8.76% of all secondary bone sarcomas treated in the same years. This incidence is the same as that of sarcomas arising on fibrous dysplasia, and is lower than those arising on bone infarcts or on Paget's disease. This possible event must be considered during follow-up of benign lesions.
Abstract: Multiple osteochondromas (MO) is an autosomal dominant disorder caused by germline mutations in EXT1 and/or EXT2. In contrast, solitary osteochondroma (SO) is nonhereditary. Products of the EXT gene are involved in heparan sulfate (HS) biosynthesis. In this study, we investigated whether osteochondromas arise via either loss of heterozygosity (2 hits) or haploinsufficiency. An in vitro three-dimensional chondrogenic pellet model was used to compare heterozygous bone marrow-derived mesenchymal stem cells (MSCs EXT(wt/-)) of MO patients with normal MSCs and the corresponding tumor specimens (presumed EXT(-/-)). We demonstrated a second hit in EXT in five of eight osteochondromas. HS chain length and structure, in vitro chondrogenesis, and EXT expression levels were identical in both EXT(wt/-) and normal MSCs. Immunohistochemistry for HS, HS proteoglycans, and HS-dependent signaling pathways (eg, TGF-β/BMP, Wnt, and PTHLH) also showed no differences. The cartilaginous cap of osteochondroma contained a mixture of HS-positive and HS-negative cells. Because a heterozygous EXT mutation does not affect chondrogenesis, EXT, HS, or downstream signaling pathways in MSCs, our results refute the haploinsufficiency theory. We found a second hit in 63% of analyzed osteochondromas, supporting the hypothesis that osteochondromas arise via loss of heterozygosity. The detection of the second hit may depend on the ratio of HS-positive (normal) versus HS-negative (mutated) cells in the cartilaginous cap of the osteochondroma.
Abstract: Tumor cell plasticity enables certain types of highly malignant tumor cells to dedifferentiate and engage a plastic multipotent embryonic-like phenotype, which enables them to 'adapt' during tumor progression and escape conventional therapeutic strategies. This plastic phenotype of aggressive cancer cells enables them to express endothelial cell-specific markers and form tube-like structures, a phenotype that has been linked to aggressive behavior and poor prognosis. We demonstrate here that the transforming growth factor (TGF)-β co-receptor endoglin, an endothelial cell marker, is expressed by tumor cells and its expression correlates with tumor cell plasticity in two types of human cancer, Ewing sarcoma and melanoma. Moreover, endoglin expression was significantly associated with worse survival of Ewing sarcoma patients. Endoglin knockdown in tumor cells interferes with tumor cell plasticity and reduces invasiveness and anchorage-independent growth in vitro. Ewing sarcoma and melanoma cells with reduced endoglin levels showed reduced tumor growth in vivo. Mechanistically, we provide evidence that endoglin, while interfering with TGF-β signaling, is required for efficient bone morphogenetic protein, integrin, focal adhesion kinase and phosphoinositide-3-kinase signaling in order to maintain tumor cell plasticity. The present study delineates an important role of endoglin in tumor cell plasticity and progression of aggressive tumors.Oncogene advance online publication, 20 September 2010; doi:10.1038/onc.2010.418.
Abstract: Myxoid liposarcoma is a relatively common malignant soft tissue tumor, characterized by a (12;16) translocation resulting in a FUS-DDIT3 fusion gene playing a pivotal role in its tumorigenesis. Treatment options in patients with inoperable or metastatic myxoid liposarcoma are relatively poor though being developed and new hope is growing.
Abstract: Primary non-Hodgkin's lymphoma of bone (PLB) is a rare subtype of primary extranodal diffuse large B cell lymphoma. PLB has morphological homogeneity and a relatively favourable clinical behaviour. Recent studies report that array-based comparative genomic hybridisation (array-CGH) analysis can be used to classify lymphomas into clinically and biologically relevant phenotypes and possibly reveal differences in oncogenic mechanisms. Here the authors performed the first array-CGH study to detect illness related genomic alterations in nine, clinically well-staged primary lymphoma of bone cases.
Abstract: Conventional osteosarcoma is characterized by rapid growth, high local aggressiveness, and metastasizing potential. Patients developing lung metastases experience poor prognosis despite extensive chemotherapy regimens and surgical interventions. Previously we identified a subgroup of osteosarcoma patients with loss of CDKN2A/p16 protein expression in the primary tumor biopsies which was significantly predictive of a very poor prognosis. Here we aimed to identify the underlying mechanism(s) of this protein loss in relation to osteosarcoma behavior. The CDKN2A locus was analyzed in osteosarcoma cases with total loss of CDKN2A/p16 expression and in cases with high protein expression using melting curve analysis-methylation assay (MCA-Meth), fluorescent in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA), and mutation analysis. All cases with complete CDKN2A/p16 protein loss showed homozygous deletions at the CDKN2A locus. In none of the cases hyper methylation of the promoter region was seen which was confirmed by sequencing this region. Taken together we show that large or smaller deletions of the CDKN2A locus are evident in patient samples and underlie the CDKN2A/p16 protein expression loss while promoter methylation does not appear to be a mechanism of this expression loss. Genomic loss of CDKN2A instead of promoter methylation might be a plausible explanation for the rapid proliferation and high aggressiveness of osteosarcoma by simultaneous impairment CDKN2A/p14(ARF) function.
Abstract: PURPOSE EWS-ETS fusion genes are the driving force in Ewing's sarcoma pathogenesis. Because of the variable breakpoint locations in the involved genes, there is heterogeneity in fusion RNA and protein architecture. Since previous retrospective studies suggested prognostic differences among patients expressing different EWS-FLI1 fusion types, the impact of fusion RNA architecture on disease progression and relapse was studied prospectively within the Euro-E.W.I.N.G. 99 clinical trial. PATIENTS AND METHODS Among 1,957 patients who registered before January 1, 2007, 703 primary tumors were accessible for the molecular biology study. Fusion type was assessed by polymerase chain reaction on frozen (n = 578) or paraffin-embedded materials (n = 125). The primary end point was the time to disease progression or relapse. Results After exclusion of noninformative patients, 565 patients were entered into the prognostic factor analysis comparing type 1 (n = 296), type 2 (n = 133), nontype 1/nontype 2 EWS-FLI1 (n = 91) and EWS-ERG fusions (n = 45). Median follow-up time was 4.5 years. The distribution of sex, age, tumor volume, tumor site, disease extension, or histologic response did not differ between the four fusion type groups. We did not observe any significant prognostic value of the fusion type on the risk of progression or relapse. The only slight difference was that the risk of progression or relapse associated with nontype 1/nontype 2 EWS-FLI1 fusions was 1.38 (95% CI, 0.96 to 2.0) times higher than risk associated with other fusion types, but it was not significant (P = .10). CONCLUSION In contrast to retrospective studies, the prospective evaluation did not confirm a prognostic benefit for type 1 EWS-FLI1 fusions.
Abstract: In its rare occurrence, Langerhans cell histiocytosis (LCH) is a dangerous but intriguing deviation of mononuclear phagocytes, especially dendritic cells (DCs). Clinically, the disease ranges from self-resolving or well manageable to severe and even fatal. LCH lesions in skin, bone, and other sites contain high numbers of cells with phenotypic features resembling LCs admixed with macrophages, T cells, eosinophils, and multinucleated giant cells. Here we review current progress in the LCH field based on two central questions: (i) are LCH cells intrinsically aberrant, and (ii) how does the lesion drive pathogenesis? We argue that LCH cells may originate from different sources, including epidermal LCs, tissue Langerin(+) DCs, or mononuclear phagocyte precursors. Current and prospective in vitro and in vivo models are discussed. Finally, we discuss recent insights into plasticity of T-helper cell subsets in light of the lesion microenvironment. LCH continues to provide urgent clinical questions thereby inspiring innovative DC lineage research.
Abstract: Sclerostin is an inhibitor of bone formation expressed by osteocytes. We hypothesized that sclerostin is expressed by cells of the same origin and also embedded within mineralized matrices. In this study, we analyzed (a) sclerostin expression using immunohistochemistry, (b) whether the genomic defect in individuals with van Buchem disease (VBD) was associated with the absence of sclerostin expression, and (c) whether this was associated with hypercementosis. Sclerostin was expressed by cementocytes in mouse and human teeth and by mineralized hypertrophic chondrocytes in the human growth plate. In individuals with VBD, sclerostin expression was absent or strongly decreased in osteocytes and cementocytes. This was associated with increased bone formation, but no overt changes in cementum thickness. In conclusion, sclerostin is expressed by all 3 terminally differentiated cell types embedded within mineralized matrices: osteocytes, cementocytes, and hypertrophic chondrocytes.
Abstract: AIM: The majority of clinicians, radiologists and pathologists have limited experience with soft tissue sarcomas. In 2004, national guidelines were established in The Netherlands to improve the quality of diagnosis and treatment of these rare tumours. This study evaluates the compliance with the guidelines over time. PATIENTS: Population-based series of 119 operated patients with a soft tissue sarcoma (STS) diagnosed in 1998-1999 (79 before implementation of new guidelines) and in 2006 (40 after implementation). METHODS: Coded information regarding patient and tumour characteristics as well as (the results of) pathology review was collected from the medical patient file by two experienced data-managers. RESULTS: Diagnostic imaging of the tumour was performed according to the guidelines in 75-100% depending on the site of the tumour (abdominal versus non-abdominal) as well as the time of diagnosis. Adherence to the guidelines with respect to invasive diagnostic procedures in patients with non-abdominal STS improved over time. A pre-operative histological diagnosis was obtained in 42% of the patients in 1998-1999 and in 72% of the patients in 2006 (p<0.001). The guidelines for reporting on pathology were increasingly adhered to. In 2006, (nearly) all pathology reports mentioned tumour size, morphology, tumour grade, resection margins and radicality. This represents a major improvement compared to the pathology reports in 1998-1999, where these aspects were not mentioned in 14-40% of the cases. The proportion of prospective pathology reviews by (a member of) the expert panel increased from 60% in 1998-1999 to 90% in 2006 (p=0.001). DISCUSSION: The compliance with the guidelines has been optimised by the increased attention to this group of patients. Most important factors have been the reporting of the results of the first evaluation and (discussions about) the centralisation of treatment. Further improvements could be reached by the prospective web based registry monitoring logistic aspects as well as parameters useful for the evaluation of the quality of care.
Abstract: PURPOSE: Altered expression of cell cycle/apoptosis key regulators may promote tumor progression, reflect secondary genetic/epigenetic events, and impair the effectiveness of therapy. Their expression pattern might then identify gastrointestinal stromal tumor (GIST) patient subgroups with different response to imatinib and elucidate novel therapeutic targets. EXPERIMENTAL DESIGN: Immunohistochemical evaluation of expression of p53, p16, p21, CHK2, CCND1, BCL2, CDK4, and MDM2 was done on 353 histologically validated GIST patients enrolled into a European/Australasian phase III trial. TP53 was screened for mutations in cases with presumptive nonfunctional protein; that is, high p53 and low expression of the two downstream molecules p21 and MDM2. Results were correlated with clinicopathologic data, KIT/PDGFRA mutation status, and imatinib dosage. RESULTS: Frequent impaired expression was found for BCL2 (78%), CHK2 (53%), p53 (50%), and p16 (47%). Stomach-originating GISTs showed significantly lower expression of p21, p16, and BCL2. KIT/PDGFRA wild-type GISTs had significant lower expression of CDK4. Eighty-eight percent of the high p53 expressers show low downstream target activation, indicating a nonfunctional p53 route. Of these high p53 expressers, 16.4% harbor a detectable TP53 mutation. Multivariate analysis, including previously identified markers, showed an independent effect of p53 and p16 on progression-free survival (PFS). Patients with high level of CHK2 and p21 showed significantly better PFS upon a high-dose regimen. CONCLUSIONS: Impaired p53, p16, BCL2, and CHK2 expression is common in advanced GISTs. Distinct patterns of expression correlate with tumor site, genotype, and PFS. Cell cycle/apoptosis maintenance is instrumental for optimal response to imatinib.
Abstract: Chondrosarcomas are notorious for their resistance to conventional chemotherapy and radiotherapy, indicating there are no curative treatment possibilities for patients with inoperable or metastatic disease. We therefore explored the existence of molecular targets for systemic treatment of chondrosarcoma using kinome profiling. Peptide array was performed for four chondrosarcoma cell lines and nine primary chondrosarcoma cultures with GIST882, MSCs, and colorectal cancer cell lines as controls. Activity of kinases was verified using immunoblot, and active Src- and platelet-derived growth factor receptor (PDGFR) signaling were further explored using imatinib and dasatinib on chondrosarcoma in vitro. The AKT1/GSK3B pathway was clearly active in chondrosarcoma. In addition, the PDGFR pathway and the Src kinase family were active. PDGFR and Src kinases can be inhibited by imatinib and dasatinib, respectively. Although imatinib did not show any effect on chondrosarcoma cell cultures, dasatinib showed a decrease in cell viability at nanomolar concentrations in seven of nine chondrosarcoma cultures. However, inhibition of phosphorylated Src (Y419) was found both in responsive and nonresponsive cells. In conclusion, using kinome profiling, we found the Src pathway to be active in chondrosarcoma. Moreover, we showed in vitro that the inhibitor of the Src pathway, dasatinib, may provide a potential therapeutic benefit for chondrosarcoma patients who are not eligible for surgery.
Abstract: Gastrointestinal stromal tumors (GISTs) metastasize primarily within the peritoneal cavity and to the liver. Superficial soft tissue metastases occur in about 1% of advanced GIST and are mostly associated with abdominal laparotomy scars and advanced disease. Extra-abdominal subcutaneous metastases of GIST have not been previously reported. Subcutaneous spindle cell tumors constitute a diagnostic challenge of which the differential diagnostic list can be limited by recognition of morphological, immunohistochemical en molecular genetic patterns. A 69-year-old woman presented with a fast growing subcutaneous nodule on her right upper arm. She was known with an imatinib-resistant advanced GIST, treated with sunitinib. The nodule was excised. Histopathological examination revealed a sharply demarcated tumor nodule in the subcutaneous fat with slightly spindled tumor cells, with pleomorphic nuclei and multiple mitoses. There was a hemangiopericytomatous vascular pattern. The cells stained positive for CD117 (KIT) and CD34. No KIT or platelet-derived growth factor receptor-alpha mutations were detected. We report the first case of an extra-abdominal subcutaneous metastasis of GIST. Although rare, metastatic GIST should therefore be included in the differential diagnosis of subcutaneous spindle cell tumors. A comparative survey of the histological, immunohistochemical and molecular genetic features of spindle cell tumors of the subcutis and a review of the literature is presented.
Abstract: PURPOSE: From February 2001 to February 2002, 946 patients with advanced GI stromal tumors (GISTs) treated with imatinib were included in a controlled EORTC/ISG/AGITG (European Organisation for Research and Treatment of Cancer/Italian Sarcoma Group/Australasian Gastro-Intestinal Trials Group) trial. This analysis investigates whether the response classification assessed by RECIST (Response Evaluation Criteria in Solid Tumors), predicts for time to progression (TTP) and overall survival (OS). PATIENTS AND METHODS: Per protocol, the first three disease assessments were done at 2, 4, and 6 months. For the purpose of the analysis (landmark method), disease response was subclassified in six categories: partial response (PR; > 30% size reduction), minor response (MR; 10% to 30% reduction), no change (NC) as either NC- (0% to 10% reduction) or NC+ (0% to 20% size increase), progressive disease (PD; > 20% increase/new lesions), and subjective PD (clinical progression). RESULTS: A total of 906 patients had measurable disease at entry. At all measurement time points, complete response (CR), PR, and MR resulted in similar TTP and OS; this was also true for NC- and NC+, and for PD and subjective PD. Patients were subsequently classified as responders (CR/PR/MR), NC (NC+/NC-), or PD. This three-class response categorization was found to be highly predictive of further progression or survival for the first two measurement points. After 6 months of imatinib, responders (CR/PR/MR) had the same survival prognosis as patients classified as NC. CONCLUSION: RECIST perfectly enables early discrimination between patients who benefited long term from imatinib and those who did not. After 6 months of imatinib, if the patient is not experiencing PD, the pattern of radiologic response by tumor size criteria has no prognostic value for further outcome. Imatinib needs to be continued as long as there is no progression according to RECIST.
Abstract: High-grade osteosarcoma is characterized by extensive genetic instability, thereby hampering the identification of causative gene mutations and understanding of the underlying pathological processes. It lacks a benign precursor lesion and reports on associations with hereditary predisposition or germline mutations are uncommon, despite the early age of onset. Here we demonstrate a novel comprehensive approach for the study of premalignant stages of osteosarcoma development in a murine mesenchymal stem cell (MSC) system that formed osteosarcomas upon grafting. By parallel functional and phenotypic analysis of normal MSCs, transformed MSCs and derived osteosarcoma cells, we provide substantial evidence for a MSC origin of osteosarcoma. In a stepwise approach, using COBRA-FISH karyotyping and array CGH in different passages of MSCs, we identified aneuploidization, translocations and homozygous loss of the cdkn2 region as the key mediators of MSC malignant transformation. We then identified CDKN2A/p16 protein expression in 88 osteosarcoma patients as a sensitive prognostic marker, thereby bridging the murine MSCs model to human osteosarcoma. Moreover, occasional reports in patients mention osteosarcoma formation following bone marrow transplantation for an unrelated malignancy. Our findings suggest a possible hazard for the clinical use of MSCs; however, they also offer new opportunities to study early genetic events in osteosarcoma genesis and, more importantly, to modulate these events and record the effect on tumour progression. This could be instrumental for the identification of novel therapeutic strategies, since the success of the current therapies has reached a plateau phase. Copyright (c) 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Abstract: AIMS: To determine prognostic significance of immunohistochemical markers and investigate possible germinal centre (GC) derivation in primary lymphoma of bone (PLB). METHODS: Immunohistochemical expression of BCL-6, CD10, BCL-2, p53, CD30, CD44 and MUM-1 was studied in 36 patients with PLB. All cases were clinically staged and cases of secondary bone involvement of primary nodal lymphomas were excluded, prior to immunostaining. Clinical charts were reviewed for clinical symptoms and therapy given; survival post-biopsy was calculated. RESULTS: All patients presented with pain and a palpable mass. The majority showed centroblastic-multilobated morphology; half of the cases (19/36) had a GC phenotype (CD10+BCL-6+ or CD10-BCL-6+MUM-1-), whereas 8/36 cases had a non-GC phenotype (CD10-BCL-6- or CD10-BCL-6+MUM-1+). Nine cases were of indeterminate phenotype (CD10-BCL-6+; MUM-1 not available). Eight of 22 evaluated patient samples showed immunoreactivity for MUM-1. Most patients (31/36) received combination therapy in the form of polychemotherapy and radiotherapy. The five-year overall survival was 75%. No significant difference in survival was found between the three different tumour phenotypes, or for the tested antigens individually. Age at presentation and stage of disease had a significant influence on five-year overall survival. Survival rates were 90% for the patients <60 years of age and 40% for those > or =60 years. Survival rates were 90% for stage I and 41% for stage IV. CONCLUSION: This study illustrates the homogeneity of PLB. The majority of cases are of the GC phenotype which has a favourable prognosis.
Abstract: Ever since Virchow introduced the entity myxoma, abundant myxoid extracellular matrix (ECM) has been recognized in various reactive and neoplastic lesions. Nowadays, the term "myxoid" is commonly used in daily pathological practice. But what do today's pathologists mean by it, and what does the myxoid ECM tell the pathologist? What is known about the exact composition and function of the myxoid ECM 150 years after Virchow? Here, we give an overview of the composition and constituents of the myxoid ECM as known so far and demonstrate the heterogeneity of the myxoid ECM among different tumors. We discuss the possible role of the predominant constituents of the myxoid ECM and attempt to relate them to differences in clinical behavior. Finally, we will speculate on the potential relevance of this knowledge in daily pathological practice.
Abstract: Benign cartilaginous tumors of bones, intrinsic to their name, are tumors forming cartilaginous matrix with a clinically benign behavior. In this group, we recognize osteochondromas, (en)chondromas, chondroblastomas, and chondromyxoid fibromas. This group includes common tumors, that is, osteochondroma and (en)chondroma as well as rare tumors such as chondroblastoma and chondromyxoid fibroma. Several benign and malignant tumors may mimic benign cartilaginous tumors of bones. We reviewed the main morphologic features and the differential diagnosis is discussed. The genetics of these tumors is intriguing ranging from single gene event (ie, EXT mutation in multiple osteochondromas) to heterogeneous rearrangements with no recurrent involved chromosomal regions such as in chondroblastoma. The main genetic findings are hereby reviewed.
Abstract: Gastrointestinal stromal tumor (GISTs) are the most common connective tissue malignancies of the gastrointestinal (GI) tract, with an incidence on the order of 10-13 per million people per year. Primary therapy is usually surgical, but the recurrence rate of large, so-called high-risk tumors, with a high mitotic rate, or those arising from small bowel and colon/rectum is particularly high. The natural history, pathology, and molecular biology of GISTs are discussed in this review, as are features of increasing our analytical power of the genes altered in these tumors, surgical issues, and the translation of research findings into clinical practice. The biological features of GIST make it a model for the examination of kinase-targeted therapeutics in solid tumors.
Abstract: ABSTRACT: BACKGROUND: Paragangliomas of the head and neck are highly vascular and usually clinically benign tumors arising in the paraganglia of the autonomic nervous system. A significant number of cases (10-50%) are proven to be familial. Multiple genes encoding subunits of the mitochondrial succinate-dehydrogenase (SDH) complex are associated with hereditary paraganglioma: SDHB, SDHC and SDHD. Furthermore, a hereditary paraganglioma family has been identified with linkage to the PGL2 locus on 11q13. No SDH genes are known to be located in the 11q13 region, and the exact gene defect has not yet been identified in this family. METHODS: We have performed a RNA expression microarray study in sporadic, SDHD- and PGL2-linked head and neck paragangliomas in order to identify potential differences in gene expression leading to tumorigenesis in these genetically defined paraganglioma subgroups. We have focused our analysis on pathways and functional gene-groups that are known to be associated with SDH function and paraganglioma tumorigenesis, i.e. metabolism, hypoxia, and angiogenesis related pathways. We also evaluated gene clusters of interest on chromosome 11 (i.e. the PGL2 locus on 11q13 and the imprinted region 11p15). RESULTS: We found remarkable similarity in overall gene expression profiles of SDHD -linked, PGL2-linked and sporadic paraganglioma. The supervised analysis on pathways implicated in PGL tumor formation also did not reveal significant differences in gene expression between these paraganglioma subgroups. Moreover, we were not able to detect differences in gene-expression of chromosome 11 regions of interest (i.e. 11q23, 11q13, 11p15). CONCLUSION: The similarity in gene-expression profiles suggests that PGL2, like SDHD, is involved in the functionality of the SDH complex, and that tumor formation in these subgroups involves the same pathways as in SDH linked paragangliomas. We were not able to clarify the exact identity of PGL2 on 11q13. The lack of differential gene-expression of chromosome 11 genes might indicate that chromosome 11 loss, as demonstrated in SDHD-linked paragangliomas, is an important feature in the formation of paragangliomas regardless of their genetic background.
Abstract: Telomeres, the ends of eukaryotic chromosomes, have been the subject of intense investigation over the last decade. As telomere dysfunction has been associated with ageing and developing cancer, understanding the exact mechanisms regulating telomere structure and function is essential for the prevention and treatment of human cancers and age-related diseases. The mechanisms by which cells maintain telomere lengthening involve either telomerase or the alternative lengthening of the telomere pathway, although specific mechanisms of the latter and the relationship between the two are as yet unknown. Many cellular factors directly (TRF1/TRF2) and indirectly (shelterin-complex, PinX, Apollo and tankyrase) interact with telomeres, and their interplay influences telomere structure and function. One challenge comes from the observation that many DNA damage response proteins are stably associated with telomeres and contribute to several other aspects of telomere function. This review focuses on the different components involved in telomere maintenance and their role in telomere length homeostasis. Special attention is paid to understanding how these telomere-associated factors, and mainly those involved in double-strand break repair, perform their activities at the telomere ends.
Abstract: OBJECTIVE: Liquid-based cytology may offer improvements over conventional cytology for cervical cancer screening. The two cytology techniques were compared in a group of 86,469 women who participated in a population-based screening program. Using a nation-wide pathology database containing both cervical cytology and histology records for all patients, we compared the outcome of the two screenings methods with regard to the detection rate of histological proven abnormalities and the determination of the true false-negative rates for both methods. METHODS: Two cohorts of women living in the same geographical region were used. Cohort 1 (n=51,154 women) was analysed using conventional cytology (conventional cohort) and cohort 2 (liquid cohort) (n=35,315 women) was analysed using liquid-based cytology (SurePath). The samples were processed in one laboratory. The results of histological follow up were available via a central database. RESULTS: The rate of unsatisfactory slides was significantly lower using liquid-based cytology (0.13% vs. 0.89%, p<0.0001). Detection of ASCUS+ (Atypical squamous cells of unknown significance or higher abnormalities) was significantly higher using liquid-based cytology (2.97% vs. 1.64%, p<0.0001), mainly due to the increase in the ASCUS category. The percentage of histological abnormalities within the ASCUS samples was approximately equal in both cohorts, indicating that more true abnormal cases were detected using liquid-based cytology. The sensitivity for detection of a histological proven lesion is significantly higher in the liquid cohort compared to the conventional cohort (96.2% vs. 92.0%), with only a slight difference in specificity (97.8% vs. 98.2%). CONCLUSION: This population study confirmed previous institution-based reports of decreased numbers of unsatisfactory samples based on liquid-based cytology and showed an increased sensitivity for the detection of cytological abnormalities that was validated by subsequent histological investigation.
Abstract: The etiology of Langerhans cell histiocytosis (LCH), a disease characterized by uncontrolled proliferation of Langerhans cells, is unknown. Although some believe that LCH is reactive, others support a neoplastic origin. We tested the hypothesis that LCH is neoplastic by investigating potential consistent chromosomal aberrations in LCH cells. We used multiparameter DNA flow cytometry to analyze the DNA ploidy LCH cells in 20 cases, performed karyotype analysis in 31 cases, array-based comparative genomic hybridization (arrayCGH) and single nucleotide polymorphism (SNP) arrays with DNA from flow-sorted CD1a-positive and CD1a-negative cells in 19 cases. Ploidy analysis revealed diploid DNA content in all cases. The karyotype of all patients analyzed was normal, excluding the presence of balanced translocations. ArrayCGH and SNP arrays did not show genome abnormalities. Despite positive TP53 protein immunohistochemical staining, sequencing of exon 5 to 8 of p53 gene showed no alterations in 7 cases. This study strongly suggests that gross chromosomal abnormalities do not cause LCH. Although we cannot exclude cryptic point mutations in as yet unidentified genes, this study of 72 LCH cases shows that LCH may be the result of restricted oligoclonal stimulation rather than unlimited neoplastic proliferation. (c) 2008 Wiley-Liss, Inc.
Abstract: The distinction between benign and malignant cartilaginous tumors of bone is one of the most difficult subjects in surgical pathology. The grading of chondrosarcoma also seems to vary considerably among pathologists. However, clinical management differs. The purpose of this study was (1) to investigate interobserver variability in histological diagnosis and grading of central cartilaginous tumors and (2) to assess the diagnostic value of defined histologic parameters in differentiating enchondroma and central grade I chondrosarcoma. The interobserver variability was assessed using a set of 16 cases evaluated by 18 specialized pathologists. Subsequently, 20 enchondromas and 37 central grade I chondrosarcomas diagnosed in a multidisciplinary team with full clinical, radiologic, and pathologic data available with 10 years of follow-up were collected. Cytologic and tissue-architectural features were assessed to find an optimal set of parameters to differentiate enchondroma from central grade I chondrosarcoma. We demonstrate considerable variation in the histologic assessment of cartilaginous tumors (weighted kappa=0.78). The distinction between enchondroma and grade I chondrosarcoma was shown to be the most disconcordant (kappa coefficient=0.54), and also the differentiation between grade I and grade II chondrosarcoma was subjected to variation (kappa coefficient=0.80). The application of a combination of 5 parameters (high cellularity, presence of host bone entrapment, open chromatin, mucoid matrix quality, and age above 45 y) allowed optimal differentiation between enchondromas and central grade I chondrosarcomas. With a classification tree based on 2 parameters (mucoid matrix degeneration more than 20% and/or host bone entrapment present), 54 of the 57 (94.7%) cases were assessed correctly (sensitivity 95% and specificity 95%). Our study confirms the low reliability of the diagnosis and grading of central chondrosarcoma. However, these classifications guide therapeutic decision making in daily practice. Therefore, we propose a classification model that, combined with a tailored radiologic assessment, may improve reliability of the diagnosis of cartilaginous tumors.
Abstract: Giant cell tumor of bone (GCTB) is a benign bone tumor with a shown clinical behavior of local recurrences and rare distant metastases. GCTB is composed of uniformly distributed osteoclastic giant cells, thought to originate from the fusion of monocyte-macrophage lineage cells, in a background consisting of mononuclear rounded cells and spindle-shaped cells. Several reports showed the specific expression of markers, such as CD14 on the mononuclear rounded cell population, however, lacking osteoclastic giant cells. Blood monocytes that were CD14+, CD33+, or CD14+/CD33+ have also been shown to be programmed as pre-osteoclasts. The macrophage marker CD33 is expressed earlier than CD14 in macrophage maturation, whereas CD14 is expressed longer than CD33. The aim of this study was to investigate CD14/CD33 expression profiles in GCTB. Nineteen GCTB tumor samples of 19 patients were studied. Immunofluorescent analyses were performed with monoclonal antibodies against CD14, CD33, RANK, and CD51. To unambiguously further prove the expression of these molecules, quantitative RT-PCR was used with subsequent sequencing of its products. All samples showed similar immunoreactivity profiles. The mononuclear rounded cell population was positive for RANK, CD51, CD14, and CD33. The osteoclastic giant cell population expressed RANK and CD51, as well as CD33, but was consistently negative for CD14 expression. The CD14 and CD33 profiles were confirmed by quantitative RT-PCR. These RT-PCR products were sequence verified. Osteoclasts in GCTB are the result of fusion of CD33-expressing pre-osteoclasts that further fuse with CD14+ mononuclear cells. Although these results reflect a static rather than a dynamic spectrum, we strongly believe that osteoclastogenesis seems not to be the exclusive result of fusion of intratumoral CD14+ mononuclear cells. Moreover, CD33-modulated osteoclastogenesis opens up the possibility for novel therapeutic directions.
Abstract: Dedifferentiated peripheral chondrosarcoma is a rare subtype of chondrosarcoma arising superimposed on the cartilage cap of a preexisting osteochondroma. It consists of two clearly defined components, a low-grade malignant, well-differentiated cartilage component and a high-grade non-cartilaginous sarcoma. Signaling pathways having a role in normal cartilage development were analyzed in these tumors, and compared with available data of other cartilaginous tumors. Sixteen well-characterized dedifferentiated peripheral chondrosarcomas were immunohistochemically analyzed for parathyroid hormone-like hormone (PTHLH)-BCL-2, fibroblastic growth factor (FGF), and transforming growth factor-beta signaling molecules, as well as matrix molecules and p53, comparing the chondrogenic component of dedifferentiated peripheral chondrosarcomas with the anaplastic component and with previously published data obtained from conventional grade I and II secondary peripheral chondrosarcomas. Results were correlated with clinical outcome. In the anaplastic component, various lines of differentiation could be found (collagen I (6/16), CD31 (1/16), smooth muscle actin (12/16), muscle-specific actin (12/16) and desmin (2/9)). Compared with the anaplastic component, the chondrogenic component of dedifferentiated peripheral chondrosarcomas shows more often expression of cyclin D1 (P=0.05), p53 (P=0.008), plasminogen activator inhibitor 1 (PAI-1) (P=0.005), and CD44 (P=0.030). Compared with secondary peripheral chondrosarcomas, more samples were positive in the chondrogenic component of dedifferentiated peripheral chondrosarcomas for FGF signaling (FGF receptor 3 P=0.000; bFGF P=0.003) and CD44 (P=0.000). Lower expression of BCL-2 (P=0.025) and absence of CD44v3 (P=0.000), a splice variant of CD44, was observed in the chondrogenic component of dedifferentiated peripheral chondrosarcomas compared with secondary peripheral chondrosarcomas. With regard to clinical data, PAI-1 expression in the chondrogenic component of dedifferentiated peripheral chondrosarcomas correlated with better survival (P=0.019). In conclusion, in the chondrogenic component of dedifferentiated peripheral chondrosarcomas, FGF signaling pathway is active, whereas PTHLH signaling seems to be low/downregulated. Interestingly, although the chondrogenic component of dedifferentiated peripheral chondrosarcoma is CD44+/CD44v3-, secondary peripheral chondrosarcomas is CD44-/CD44v3+, which suggest different splicing (preference). The prognostic value of PAI-1 in dedifferentiated peripheral chondrosarcomas might also be of interest for the more common dedifferentiated central chondrosarcomas.Modern Pathology advance online publication, 4 September 2009; doi:10.1038/modpathol.2009.120.
Abstract: The tumor suppressor genes EXT1 and EXT2 are involved in the formation of multiple osteochondromas, which can progress to become secondary peripheral chondrosarcomas. The most common chondrosarcoma subtype is primary central chondrosarcoma, which occurs in the medullar cavity of bone. The EXT1/EXT2 protein complex is involved in heparan sulfate proteoglycan (HSPG) biosynthesis, which is important for signal transduction of Indian hedgehog (IHH), WNT, and transforming growth factor (TGF)-beta. The role of EXT and its downstream targets in central chondrosarcomas is currently unknown. EXT1 and EXT2 were therefore evaluated in central chondrosarcomas at both the DNA and mRNA levels. Immunohistochemistry was used to assess HSPG (CD44v3 and SDC2), WNT (beta-catenin), and TGF-beta (PAI-1 and phosphorylated Smad2) signaling, whereas IHH signaling was studied both by quantitative polymerase chain reaction and in vitro. mRNA levels of both EXT1 and EXT2 were normal in central chondrosarcomas; genomic alterations were absent in these regions and in 30 other HSPG-related genes. Although HSPGs were aberrantly located (CD44v3 in the Golgi and SDC2 in cytoplasm and nucleus), this was not caused by mutation. WNT signaling negatively correlated with increasing histological grade, whereas TGF-beta positively correlated with increasing histological grade. IHH signaling was active, and inhibition decreased cell viability in one of six cell lines. Our data suggest that, despite normal EXT in central chondrosarcomas, HSPGs and HSPG-dependent signaling are affected in both central and peripheral chondrosarcomas.
Abstract: Cellular myxoma and grade I myxofibrosarcoma are mesenchymal tumours that are characterized by their abundant myxoid extracellular matrix (ECM). Despite their histological overlap, they differ clinically. Diagnosis is therefore difficult though important. We investigated their (cyto) genetics and ECM. GNAS1-activating mutations have been described in intramuscular myxoma, and lead to downstream activation of cFos. KRAS and TP53 mutations are commonly involved in sarcomagenesis whereby KRAS subsequently activates c-Fos. A well-documented series of intramuscular myxoma (three typical cases and seven cases of the more challenging cellular variant) and grade I myxofibrosarcoma (n = 10) cases were karyotyped, analyzed for GNAS1, KRAS and TP53 mutations and downstream activation of c-Fos mRNA and protein expression. ECM was studied by liquid chromatography mass spectrometry and expression of proteins identified was validated by immunohistochemistry and qPCR. Grade I myxofibrosarcoma showed variable, non-specific cyto-genetic aberrations in 83,5% of cases (n = 6) whereas karyotypes of intramuscular myxoma were all normal (n = 7). GNAS1-activating mutations were exclusively found in 50% of intramuscular myxoma. Both tumour types showed over-expression of c-Fos mRNA and protein. No mutations in KRAS codon 12/13 or in TP53 were detected. Liquid chromatography mass spectrometry revealed structural proteins (collagen types I, VI, XII, XIV and decorin) in grade I myxofibrosarcoma lacking in intramuscular myxoma. This was confirmed by immunohistochemistry and qPCR. Intramuscular/cellular myxoma and grade I myxofibrosarcoma show different molecular genetic aberrations and different composition of their ECM that probably contribute to their diverse clinical behaviour. GNAS1 mutation analysis can be helpful to distinguish intramuscular myxoma from grade I myxofibrosarcoma in selected cases.
Abstract: PURPOSE: Ewing sarcoma is an aggressive sarcoma and is the second most common bone sarcoma in childhood. Disease-specific t(11;22) ( approximately 85-90%), t(21;22) ( approximately 5-10%), or rarer variant translocations with the involvement of chromosome 22 ( approximately 5%) are present. At the gene level, the EWSR1 gene fuses with FLI1, ERG, or other ETS transcription factor family members. Thus far, no Ewing sarcoma has been identified with a fusion to transcription factors other than ETS. EXPERIMENTAL DESIGN: Using molecular tools such as multicolor fluorescence in situ hybridization and array comparative genomic hybridization, a ring chromosome containing chromosomes 20 and 22 was identified in four Ewing sarcoma cases. The breakpoint was mapped with (fiber-) fluorescence in situ hybridization and reverse transcription-PCR followed by sequencing of the fusion partners. RESULTS: Molecular karyotyping showed the translocation and amplification of regions of chromosomes 20q13 and 22q12. Cloning of the breakpoint showed an in-frame fusion between the EWSR1 and NFATc2 genes, resulting in loss of the NH(2)-terminal, calcineurin-dependent control region and an intact active domain of NFATc2 controlled by the transactivation domains of EWSR1. CONCLUSION: A new translocation involving EWSRI and NFATc2 was cloned. NFATc2 is a transcription factor that is not a member of the ETS family and functions in T-cell differentiation and immune response. Direct involvement of NFATc2 has not yet been observed in oncogenesis. We show that due to the shared sequence recognition of NFATc2 and the ETS family, shared transcriptional control is possible using activating protein complex 1.
Abstract: Ewing sarcoma (EWS) is a tumour most commonly arising in bone, although on occasion in soft tissue, with a poor prognosis in patients with refractory or relapsed disease, despite multimodal therapy. Immunotherapeutic strategies based on tumour-reactive T and/or natural killer cells may improve the treatment of advanced-stage EWS. Since cellular immune recognition critically depends on human leukocyte antigen (HLA) expression, knowledge about HLA expression in EWS is crucial in the design of cellular immunotherapeutic strategies. Constitutive and IFNgamma-induced HLA class I expression was analysed in EWS cell lines (n = 6) by flow cytometry, using antibodies against both monomorphic and allele-specific antigens. Expression of antigen processing pathway components and beta-2 microglobulin (beta2m) was assessed by western blot. Expression of class II transactivator (CIITA), and its contribution to HLA class II expression, was evaluated by qRT-PCR, transduction assays, and flow cytometry. beta2m/HLA class I and class II expression was validated in EWS tumours (n = 67) by immunofluorescence. Complete or partial absence of HLA class I expression was observed in 79% of EWS tumours. Lung metastases consistently lacked HLA class I and sequential tumours demonstrated a tendency towards decreased expression upon disease progression. Together with absent or low constitutive expression levels of specific HLA class I loci and alleles, and differential induction of identical alleles by IFNgamma in different cell lines, these results may reflect the existence of an immune escape mechanism. Inducible expression of TAP-1/-2, tapasin, LMP-2/-7, and the beta2m/HLA class I complex by IFNgamma suggests that regulatory mechanisms are mainly responsible for heterogeneity in constitutive class I expression. EWSs lack IFNgamma-inducible HLA class II, due to lack of functional CIITA. The majority of EWS tumours, particularly if advanced-stage, exhibit complete or partial absence of both classes of HLA. This knowledge will be instrumental in the design of cellular immunotherapeutic strategies for advanced-stage EWS.
Abstract: Genetic instability in relation to clinical behavior was studied in 52 cases of giant cell tumor of bone (GCTB). Ploidy was determined in the mononuclear cell population by using native cell smears and image cytometry. A relocalization technique allowed fluorescent in situ hybridization (FISH) analysis of CD68-negative neoplastic cells for numerical changes of chromosomes X, 3, 4, 6, 11, and telomeric association on 11p. Genome-wide alterations were tested using array comparative genomic hybridization (array-CGH) on magnetically separated CD68-negative tumor cells. CTNNB1, TP53, and BCL2 protein expression was also analyzed in formol-paraffin sections to see if their pathways are involved in the development of chromosomal instability. CD68-positive histiocytes showed no significant numerical chromosome and telomeric alterations. Based on ploidy values and clinical outcome, we could distinguish five groups as follows: diploid nonrecurrent (n = 20), tetraploid nonrecurrent (n = 6), diploid recurrent (n = 5), tetraploid and/or aneuploid recurrent (n = 14), and malignant cases (n = 7). Random individual-cell aneusomy was significantly (P < 0.001) more frequent in the recurrent groups (36.01 +/- 11.94%) than in the benign nonrecurrent cases (10.65 +/- 3.66%). The diploid recurrent group showed significantly (P < 0.001) increased balanced aneusomy compared with the diploid nonrecurrent group and the tetraploid nonrecurrent group represented eusomic polysomy. Array-CGH and FISH showed clonal aberrations almost exclusively in the malignant group. None of the protein markers tested showed significant correlation with elevated aneuploidy/polysomy (P = 0.56). Our results show that ploidy determination combined with FISH analysis may help predicting recurrence potential of GCTB and suggest that chromosomal abnormalities superimposed on telomeric associations could be responsible for an aggressive clinical course.
Abstract: PURPOSE: Histologic grade is currently the best predictor of clinical course in chondrosarcoma patients. Grading suffers, however, from extensive interobserver variability and new objective markers are needed. Hence, we have investigated DNA copy numbers in chondrosarcomas with the purpose of identifying markers useful for prognosis and subclassification. EXPERIMENTAL DESIGN: The overall pattern of genomic imbalances was assessed in a series of 67 chondrosarcomas using array comparative genomic hybridization. Statistical analyses were applied to evaluate the significance of alterations detected in subgroups based on clinical data, morphology, grade, tumor size, and karyotypic features. Also, the global gene expression profiles were obtained in a subset of the tumors. RESULTS: Genomic imbalances, in most tumors affecting large regions of the genome, were found in 90% of the cases. Several apparently distinctive aberrations affecting conventional central and peripheral tumors, respectively, were identified. Although rare, recurrent amplifications were found at 8q24.21-q24.22 and 11q22.1-q22.3, and homozygous deletions of loci previously implicated in chondrosarcoma development affected the CDKN2A, EXT1, and EXT2 genes. The chromosomal imbalances in two distinct groups of predominantly near-haploid and near-triploid tumors, respectively, support the notion that polyploidization of an initially hyperhaploid/hypodiploid cell population is a common mechanism of chondrosarcoma progression. Increasing patient age as well as tumor grade were associated with adverse outcome, but no copy number imbalance affected metastasis development or tumor-associated death. CONCLUSION: Despite similarities in the overall genomic patterns, the present findings suggest that some regions are specifically altered in conventional central and peripheral tumors, respectively.
Abstract: AIM: Myxoid tumours of soft tissue are characterized by their so-called 'myxoid' extracellular matrix. The aim was to investigate the composition and possible function of this matrix which is poorly understood. METHODS AND RESULTS: Using Alcian Blue staining with and without pretreatment with hyaluronidase and application of the critical electrolyte concentration method followed by densitometry, the glycosaminoglycan composition of three different myxoid tumours was studied. The composition of glycosaminoglycans varied with tumour type and grade, despite their general characterization as myxoid tumours. Intramuscular myxoma contained similar amounts of the various glycosaminoglycans as grade I myxofibrosarcoma; grade III myxofibrosarcoma contained less hyaluronic acid and more heparan sulphate, whereas extraskeletal myxoid chondrosarcoma contained predominantly chondroitin-4 and -6 sulphates. Western blot identified albumin as a major protein in tumour lysates, and its presence in the extracellular matrix and cytoplasm of the majority of tumours was demonstrated by immunohistochemistry; production of albumin by the tumour cells was confirmed by quantitative polymerase chain reaction. CONCLUSIONS: The extracellular matrix of myxoid tumours of soft tissue has a heterogeneous composition consisting of, amongst others, glycosaminoglycans and albumin, which appear to play an active role in their morphogenesis.
Abstract: RATIONALE: The 62005 EORTC phase III trial, comparing two doses of imatinib in patients with advanced GIST, reported a median progression-free survival of 25 months with a trend towards dose dependency for progression-free survival. The current analysis of that study aimed to assess whether histological/immunohistochemical parameters correlate with clinical response to imatinib. PATIENTS AND METHODS: Pre-treatment samples of GISTs from 546 patients enroled in phase III study were analysed for immunohistochemical characteristics, correlations with clinicopathological data, with survival and with tumours' genotype. RESULTS: There was no correlation between immunomorphological or clinical characteristics and response to treatment, PFS or OS. No correlations between immunophenotype of the tumour and PFS or OS in the two dose arms were observed. CONCLUSIONS: The results confirm the heterogeneity of GIST in terms of immunophenotypic expression, but indicate that these parameters have no impact on the outcome of the patients under imatinib treatment.
Abstract: INTRODUCTION: Ewing sarcoma (EWS) is a malignant bone-associated sarcoma, with poor prognosis in case of metastasis or relapse. To explore the feasibility of natural killer (NK) cell mediated immunotherapy and to identify molecular mechanisms involved, the susceptibility of EWS to NK cells was investigated. METHODS AND RESULTS: All EWS cell lines tested (n=7) were lysed by purified allogeneic NK cells from healthy donors, and the efficacy of lysis was increased by activating NK cells with interleukin-15 (IL-15). FACS analysis and immunohistochemistry revealed that EWS cell lines as well as primary tumor cells expressed ligands for the activating NK cell receptors NKG2D and DNAM-1. NK cell cytotoxicity to EWS cells critically depended on the combination of NKG2D and DNAM-1 signaling, since blocking either of these receptors abrogated lysis by resting NK cells. Cytokine-activated NK cells more efficiently recognized EWS cells, since only combined, but not single blockade of NKG2D and DNAM-1 by antibodies inhibited lysis of EWS cells. Induction or blockade of HLA class I on EWS cells did not significantly influence lysis. This suggests that predominantly activating, rather than inhibitory signals on EWS cells determined susceptibility to NK cell cytotoxicity. NK cell cytotoxicity to EWS cells and K562 was reduced in EWS patients at diagnosis (n=11) compared to age matched controls, despite normal NK cell numbers and increased expression of NKG2D. The impaired function of these NK cells was restored after activation with IL-15 in vitro. CONCLUSION: These results demonstrate that EWS cells are potentially susceptible to NK cell cytotoxicity due to the expression of activating NK cell receptor ligands. The use of cytokine-activated NK cells rather than resting NK cells in immunotherapy may be instrumental to optimize NK cell reactivity to EWS.
Abstract: RATIONALE: Angiosarcomas of soft tissue represent a heterogenous group of rare sarcomas with specific clinical behaviour and risk factors. Paclitaxel appears to induce tumour control in a higher proportion of patients with angiosarcoma, as compared to other sarcomas. The objective of this retrospective study was to assess the anti-tumour activity of this compound in a multicentre setting. METHOD: Clinical data from patients with angiosarcomas of soft tissue treated with single agent paclitaxel were collected from the centres of the soft tissue and bone sarcoma group of EORTC, using a standardised data collection form. Paclitaxel could be given every three weeks, or weekly. Statistical analysis was performed using SAS software. RESULTS: Data from 32 patients were collected from 10 centres. There were 17 males, 15 females, with a median age of 60.4 years (range, 25-91). Primary angiosarcomas were located in scalp and face in 8 patients (25%) and at other primary sites in 24 patients (75%). All patients had intermediate (n=13) or high grade (n=19) primary tumours. Thirteen (40%) patients had been pretreated with doxorubicin-based first-line-chemotherapy and three of them (9%) had also received second-line chemotherapy with ifosfamide. Eleven (34%) patients had been irradiated before as treatment for angiosarcoma. In 8 (25%) patients, the angiosarcoma occurred at sites of prior radiation therapy for other malignancies. The response rate was 62% (21/32) in the whole series, 75% (6/8) in scalp angiosarcomas and 58% (14/24) in other primary sites. The median time to progression was 7.6 months (range, 1-42) for the whole group. For the face/scalp group it was 9.5 months, and for patients with angiosarcomas at other sites it was 7.0 months, respectively. CONCLUSION: Paclitaxel was found to be an active agent in angiosarcoma of soft tissue in this retrospective analysis. These results need to be confirmed in a prospective randomised phase II study.
Abstract: OBJECTIVE: Cholesterol ester transfer protein (CETP) plays an important role in HDL cholesterol metabolism. Leucocytes, including monocyte-derived macrophages in the arterial wall synthesize and secrete CETP, but its role in atherosclerosis is unclear. The aim of the current study was to investigate the effect of acute coronary syndromes (ACS) on leucocyte CETP expression. RESEARCH DESIGN: Peripheral blood mononuclear cells (PBMCs) were freshly isolated from hospitalized ACS patients displaying Braunwald class IIIB unstable angina pectoris (UAP) on admission (t = 0) and at 180 days post inclusion (t = 180) for analysis of CETP expression. In addition, to prove the potential correlation between leucocyte CETP and ACS the effect of acute myocardial infarction on leucocyte CETP expression was studied in CETP transgenic mice. RESULTS: Upon admission, UAP patients displayed approximately 3-6 fold (P < 0.01) lower CETP mRNA and nearly absent CETP protein expression in PBMCs, as compared to healthy age-/sex-matched controls. Interestingly, CETP mRNA and protein levels were significantly elevated in PBMCs isolated from UAP patients (both stabilized and refractory) at t = 180 as compared to t = 0 (P < 0.01), which was correlated with a reduced inflammatory status after medical treatment. In agreement with the data obtained in UAP patients, markedly down-regulated leucocyte CETP mRNA expression was observed after coronary artery ligation in CETP transgenic mice, which also correlated with increased serum amyloid A levels. CONCLUSIONS: We are the first to report that episodes of UAP in humans and myocardial infarction in CETP transgenic mice are associated with reduced leucocyte CETP expression. We propose that the impairment in leucocyte CETP production is associated with an enhanced inflammatory status, which could be clinically relevant for the pathogenesis of ACS.
Abstract: Chondrosarcomas are highly resistant to conventional radiation and chemotherapy and surgical removal is the only option for curative treatment. Consequently, there is nothing to offer patients with inoperable tumours and metastatic disease. The aim of this study is to investigate genes involved in cell cycle control: CDK4, CDKN2A/p16, cyclin D1, p21, p53, MDM2 and c-MYC, which may point towards new therapeutic strategies. The pRb pathway was targeted using CDKN2A/p16 overexpressing vectors and shRNA against CDK4 in chondrosarcoma cell lines OUMS27, SW1353, and CH2879. Cell survival and proliferation were assessed. CDK4, MDM2 and c-MYC expression levels were investigated by qPCR and immunohistochemistry (IHC) in 34 fresh frozen and 90 FFPE samples of enchondroma and chondrosarcoma patients. On a subset of 29 high grade chondrosarcomas IHC for cyclin D1, p21 and p53 was performed. Overexpression of CDKN2A/p16 and knock down of CDK4 by shRNA in OUMS27, SW1353, and CH2879 resulted in a significant decrease in cell viability and proliferation and a decreased ability to form colonies in vitro. Expression of CDK4 and MDM2 was associated with high-grade chondrosarcoma both at the mRNA and protein level. Combining these results with the expression of cyclin D1 and the previously shown loss of CDKN2A/p16 expression show that the majority (96%; 28/29) of high-grade chondrosarcomas contain alterations in the pRb pathway.This suggests a role for the use of CDK4 inhibitors as a treatment of metastatic or inoperable high-grade chondrosarcoma.
Abstract: This review provides an overview of the histopathology, classification, diagnostic procedures, and therapy of skeletal chondrosarcoma. Chondrosarcomas that arise de novo are primary chondrosarcomas, whereas chondrosarcomas developing superimposed on pre-existing benign cartilage neoplasms such as enchondromas or osteochondromas are referred to as secondary chondrosarcomas. Conventional chondrosarcomas can be categorized according to their location in bone into central, peripheral, and juxtacortical chondrosarcomas. Histological grading is related to prognosis; however, it is also subject to interobserver variability. Rare subtypes of chondrosarcoma, including dedifferentiated, mesenchymal, and clear cell chondrosarcoma, are discussed as well. Magnetic resonance imaging is necessary to delineate the extent of the intraosseous and soft tissue involvement preoperatively. Computed tomography is especially recommended in the pelvis and other flat bones where it may be difficult to discern the pattern of bone destruction and the presence of matrix mineralization. Wide, en-bloc excision is the preferred surgical treatment in intermediate- and high-grade chondrosarcoma. In low-grade chondrosarcoma confined to the bone, extensive intralesional curettage followed by local adjuvant treatment and filling the cavity with bone graft has promising long-term clinical results and satisfactory local control. Chondrosarcomas are relatively radiotherapy resistant; therefore, doses >60 Gy are needed in attempts to achieve local control after incomplete resection. Irradiation with protons or other charged particles seems beneficial in this curative situation. Chemotherapy is only possibly effective in mesenchymal chondrosarcoma, and is of uncertain value in dedifferentiated chondrosarcoma. Potential new systemic treatment targets are being discussed.
Abstract: There is controversy regarding whether lymphatic vessels are present or absent in bone. Although lymphangiomas have been described in bone, lymphatic vessels have not been identified morphologically with certainty in any other benign or malignant bone tumors or in normal human bone. In this study, we determined by immunohistochemistry, using 2 specific lymphatic endothelial cell markers, LYVE-1 and podoplanin, whether lymphatics are present in normal bone and a wide range of primary and secondary bone neoplasms. In normal bone, LYVE-1+/podoplanin+ lymphatic vessels were not identified in cortical or cancellous bone but were seen in connective tissue overlying the periosteum. With the exception of lymphangioma, Gorham-Stout disease, and hemangioendothelioma, primary benign and malignant bone tumors (as well as secondary carcinomas) that were confined to bone did not contain lymphatic vessels. Primary and secondary bone tumors that had extended through the bone cortex contained LYVE-1+/podoplanin+ lymphatic vessels that seemed to extend for a short distance from surrounding soft tissues into the tumor. Three cases of osteosarcoma that had extended through the bone cortex and had lymph node metastases were all found to contain lymphatic vessels within the tumor. These results indicate that the lymphatic circulation is unlikely to play a role in bone fluid transport in normal bone and that lymphatic vessels are absent from most primary and secondary tumors confined to bone. These findings also suggest that lymphangiogenesis is not involved in the disease progression of most primary bone tumors and that carcinomatous metastasis to bone does not occur via lymphatics.
Abstract: The initiating somatic genetic events in chordoma development have not yet been identified. Most cytogenetically investigated chordomas have displayed near-diploid or moderately hypodiploid karyotypes, with several numerical and structural rearrangements. However, no consistent structural chromosome aberration has been reported. This is the first array-based study characterising DNA copy number changes in chordoma. Array comparative genomic hybridisation (aCGH) identified copy number alterations in all samples and imbalances affecting 5 or more out of the 21 investigated tumours were seen on all chromosomes. In general, deletions were more common than gains and no high-level amplification was found, supporting previous findings of primarily losses of large chromosomal regions as an important mechanism in chordoma development. Although small imbalances were commonly found, the vast majority of these were detected in single cases; no small deletion affecting all tumours could be discerned. However, the CDKN2A and CDKN2B loci in 9p21 were homo- or heterozygously lost in 70% of the tumours, a finding corroborated by fluorescence in situ hybridisation, suggesting that inactivation of these genes constitute an important step in chordoma development.
Abstract: Giant cell tumour of bone (GCTB) is a benign bone tumour known for the unpredictable clinical behaviour of recurrences and, in rare instances, distant metastases. It consists of uniformly distributed osteoclastic giant cells in a background of mononuclear rounded and spindle-shaped cells. Cytogenetically, telomeric associations are the most common chromosomal aberrations, which, however, are normally almost exclusively found in high-grade malignancies. GCTB has often been regarded as a polyclonal tumour, but more recently a recurrent specific aberration was reported, which suggests a possible role for disturbed telomere maintenance. Here we further investigate telomere maintenance in GCTB using 19 samples from 19 patients. A combination of immunofluorescence and FISH was performed, applying antibodies directed against promyelocytic leukaemia body-related antigen and hTERT and using telomere peptide nucleic acid probes. The TRAP assay and telomere restriction fragment length analysis were performed for functional detection of telomerase activity and alternative telomere lengthening. Both osteoclastic giant cells and mononuclear cells showed positivity for hTERT and promyelocytic leukaemia body-related antigen. In most mononuclear cells, co-expression was present. The TRAP assay demonstrated heterogeneous telomerase activity, while telomere restriction fragment length analysis showed non-heterogeneous telomere lengths, indicating the absence of alternative telomere lengthening. Confocal microscopy showed stereometric co-localization of nucleolin with promyelocytic leukaemia body-related antigen in association with telomeres in the spindle-shaped cells. hTERT was more diffusely distributed throughout the nucleus. Our results show that GCTB demonstrates remarkable telomere maintenance of activated telomerase and inactivated alternative telomere lengthening in the presence of normal mean telomere restriction fragment lengths. These findings strongly suggest that these aggregates, while activating telomerase, are part of a structural telomere protective-capping mechanism rather than of a telomere-lengthening mechanism. Telomere maintenance could be considered an important key factor in the pathogenesis of GCTB.
Abstract: Surgery is considered to be the most effective treatment for cartilaginous tumours. In recent years, a trend has emerged for patients with low-grade tumours to be treated less invasively using curettage followed by various forms of adjuvant therapy. We investigated the potential for phenol to be used as an adjuvant. Using a human chondrosarcoma-derived cartilage-producing cell line OUMS-27 as an in vitro model we studied the cytotoxic effect of phenol and ethanol. Since ethanol is the standard substance used to rinse phenol out of a bone cavity, we included an assessment of ethanol to see whether this was an important secondary factor with respect to cell death. The latter was assessed by flow cytometry. A cytotoxic effect was found for concentrations of phenol of 1.5% and of ethanol of 42.5%. These results may provide a clinical rationale for the use of both phenol and ethanol as adjuvant therapy after intralesional curettage in low-grade central chondrosarcoma and justify further investigation.
Abstract: PURPOSE: Angiomatoid fibrous histiocytoma (AFH) is a low-grade mesenchymal neoplasm which usually occurs in children and adolescents. Either FUS-ATF1 or EWSR1-ATF1 have been detected in the few cases published, pointing to the interchangeable role of FUS and EWSR1 in this entity. EWSR1-ATF1 also represents the most frequent genetic alteration in clear cell sarcoma, suggesting the existence of a molecular homology between these two histotypes. We investigated the presence of EWSR1-CREB1, recently found in gastrointestinal clear cell sarcoma, and FUS-CREB1, as well as the already reported FUS-ATF1 and EWSR1-ATF1 in a series of AFH. EXPERIMENTAL DESIGN: Fourteen cases were analyzed by fluorescence in situ hybridization (FISH) on paraffin-embedded tissue sections, using a commercial EWSR1 probe and custom-designed probes for FUS, ATF1, and CREB1. In two cases, four-color FISH was also done. Reverse transcription-PCR for the four hypothetical fusion genes was done in one case, for which frozen material was available. RESULTS: Thirteen cases showed rearrangements of both EWSR1 and CREB1, whereas one case showed the rearrangement of both EWSR1 and ATF1. Four-color FISH confirmed the results in two selected cases. Reverse transcription-PCR showed EWSR1-CREB1 transcript in the case analyzed. CONCLUSION: We identified the presence of either EWSR1-CREB1 or EWSR1-ATF1 in all the cases, strengthening the concept of chromosomal promiscuity between AFH and clear cell sarcoma. Either the occurrence of a second unknown tumor-specific molecular event or, perhaps more likely, divergent differentiation programs of the putatively distinct precursor cells of AFH and clear cell sarcoma might be invoked in order to explain the two different phenotypes.
Abstract: Purpose. This review summarizes the more prevalent soft tissue tumours arising in the retroperitoneum and highlights some recent fundamental and diagnostic developments relevant to mesenchymal tumours.Discussion. The retroperitoneum is an underestimated site for benign and malignant neoplastic disease, and represents the second most common site of origin of primary malignant soft tissue tumours (sarcomas) after the deep tissues of the lower extremity. In contrast to the predominance of benign soft tissue lesions over malignant sarcomas elsewhere, retroperitoneal mesenchymal lesions are far more likely to be malignant. The differential diagnosis is primarily with the more common lymphoproliferative and parenchymatous epithelial lesions arising in this area, and with metastatic disease from known or unknown primary sites elsewhere.The most prevalent mesenchymal tumours at this site are of a lipomatous, myogenic or neural nature.Their generally late clinical presentation and poorly accessible location provides numerous clinical challenges; optimal radiological imaging and a properly performed biopsy are essential cogs in the management route. Histopathological diagnosis may be complicated, but has been aided by developments in the fields of immunohistochemistry and tumour (cyto)genetics. Despite significant advances in oncological management protocols, the prognosis remains generally less favourable than for similar tumours at more accessible sites.
