Establishment of a new continuous clear cell sarcoma cell line. Morphological and cytogenetic characterization and detection of chimaeric EWS/ATF-1 transcripts

Functional genomics of human clear cell sarcoma: genomic, transcriptomic and chemical biology landscape for clear cell sarcoma

BACKGROUND

Systemic therapy for metastatic clear cell sarcoma (CCS) bearing EWSR1-CREB1/ATF1 fusions remains an unmet clinical need in children, adolescents, and young adults.

METHODS

To identify key signaling pathway vulnerabilities in CCS, a multi-pronged approach was taken: (i) genomic and transcriptomic landscape analysis, (ii) integrated chemical biology interrogations, (iii) development of CREB1/ATF1 inhibitors, and (iv) antibody-drug conjugate testing (ADC). The first approach encompassed DNA exome and RNA deep sequencing of the largest human CCS cohort yet reported consisting of 47 patient tumor samples and 8 cell lines.

RESULTS

Sequencing revealed recurrent mutations in cell cycle checkpoint, DNA double-strand break repair or DNA mismatch repair genes, with a correspondingly low to intermediate tumor mutational burden. DNA multi-copy gains with corresponding high RNA expression were observed in CCS tumor subsets. CCS cell lines responded to the HER3 ADC patritumab deruxtecan in a dose-dependent manner in vitro, with impaired long term cell viability.

CONCLUSION

These studies of the genomic, transcriptomic and chemical biology landscape represent a resource 'atlas' for the field of CCS investigation and drug development. CHK inhibitors are identified as having potential relevance, CREB1 inhibitors non-dependence of CCS on CREB1 activity was established, and the potential utility of HER3 ADC being used in CCS is found.

Uncommon Histopathological Variants of Malignant Melanoma: Part 1

Despite new horizons opened by recent advances in molecular pathology, histological evaluation still remains the diagnostic gold standard regarding cutaneous melanocytic neoplasms. Several histological variants of melanoma have been described, and their knowledge is crucial for accurate diagnosis and classification of cases with unusual clinicopathological features. Uncommon histological variants of melanoma have been described based on a broad constellation of features, including architectural pattern, stromal alterations, cytological attributes, and other morphological properties. This review is aimed at providing an extensive discussion of unusual but distinctive histopathological variants of melanoma.

Establishment and proteomic characterization of patient-derived clear cell sarcoma xenografts and cell lines

Clear cell sarcoma (CCS) is an aggressive mesenchymal malignancy characterized by the unique chimeric EWS-ATF1 fusion gene. Patient-derived cancer models are essential tools for the understanding of tumorigenesis and the development of anti-cancer drugs; however, only a limited number of CCS cell lines exist. The objective of this study was to establish patient-derived CCS models. We established patient-derived CCS models from a 43-yr-old female patient. We prepared the patient-derived xenografts (PDXs) from tumor tissues obtained through biopsy or surgery and isolated stable cell lines from PDXs and the original tumor tissue. The presence of gene fusions was examined by RT-PCR, and Sanger sequencing. The established cell lines were characterized by short tandem repeat, viability, colony and spheroid formation, and invasion analyses. Differences in gene enrichment between the primary tumor and cell lines were examined by mass spectrometry and KEGG pathway analysis. The cell lines were maintained for more than 80 passages, and had tumorigenic characteristics such as colony and spheroid formation and invasion. Mass spectrometric proteome analysis demonstrated that the cell lines were enriched for similar but distinct molecular pathways, compared to those in the xenografts and original tumor tissue. Next, tyrosine kinase inhibitors were screened for their suppressive effects on viability. We found that ponatinib, vandetanib, and doxorubicin suppressed the growth of cell lines, and had equivalent IC₅₀ values. Further in-depth investigation and understanding of drug-sensitivity mechanisms will be important for the clinical applications of our cell lines.

Non-mesenchymal Mimics of Sarcoma

A variety of different non-mesenchymal neoplasms may mimic sarcoma, in particular sarcomatoid carcinoma and melanoma, but also mesothelioma and rarely some lymphomas. This article reviews the key clinical and histologic features of such neoplasms in different settings, along with the use of ancillary studies to help identify the tumor types most frequently misdiagnosed as sarcoma.

Establishment of a novel clear cell sarcoma cell line (Hewga-CCS), and investigation of the antitumor effects of pazopanib on Hewga-CCS

Background

Clear cell sarcoma (CCS) is a therapeutically unresolved, aggressive, soft tissue sarcoma (STS) that predominantly affects young adults. This sarcoma is defined by t(12;22)(q13;q12) translocation, which leads to the fusion of Ewing sarcoma gene (EWS) to activating transcription factor 1 (ATF1) gene, producing a chimeric EWS-ATF1 fusion gene. We established a novel CCS cell line called Hewga-CCS and developed an orthotopic tumor xenograft model to enable comprehensive bench-side investigation for intensive basic and preclinical research in CCS with a paucity of experimental cell lines.

Methods

Hewga-CCS was derived from skin metastatic lesions of a CCS developed in a 34-year-old female. The karyotype and chimeric transcript were analyzed. Xenografts were established and characterized by morphology and immunohistochemical reactivity. Subsequently, the antitumor effects of pazopanib, a recently approved, novel, multitargeted, tyrosine kinase inhibitor (TKI) used for the treatment of advanced soft tissue sarcoma, on Hewga-CCS were assessed in vitro and in vivo.

Results

Hewga-CCS harbored the type 2 EWS-ATF1 transcript. Xenografts morphologically mimicked the primary tumor and expressed S-100 protein and antigens associated with melanin synthesis (Melan-A, HMB45). Pazopanib suppressed the growth of Hewga-CCS both in vivo and in vitro. A phospho-receptor tyrosine kinase array revealed phosphorylation of c-MET, but not of VEGFR, in Hewga-CCS. Subsequent experiments showed that pazopanib exerted antitumor effects through the inhibition of HGF/c-MET signaling.

Conclusions

CCS is a rare, devastating disease, and our established CCS cell line and xenograft model may be a useful tool for further in-depth investigation and understanding of the drug-sensitivity mechanism.

Molecular strategies for detecting chromosomal translocations in soft tissue tumors (review)

Approximately one third of soft tissue tumors are characterized by chromosomal aberrations, in particular, translocations and amplifications, which appear to be highly specific. The identification of fusion transcripts not only supports the diagnosis, but provides the basis for the development of novel therapeutic strategies aimed at blocking the aberrant activity of chimeric proteins. Molecular biology, and in particular, cytogenetic and qualitative and quantitative polymerase chain reaction technologies, allow with high efficiency and specificity, the determination of specific fusion transcripts resulting from chromosomal translocations, as well as the analysis of gene amplifications. In this review, various molecular techniques that allow the identification of translocations and consequent fusion transcripts generated are discussed in the broad spectrum of soft tissue tumors.

Mesenchymal Tumors of the Gastrointestinal Tract Other than GIST

Mesenchymal tumors involve the gastrointestinal (GI) tract more frequently than other visceral organs. Many such tumors are small, and are benign and increasingly being detected incidentally during colonoscopic screening. Some tumors show distinctive features at this site, such as schwannoma and clear cell sarcoma-like tumor of the GI tract. Without knowledge of these features, recognition of these tumor types can be difficult. This reviews addresses recent developments and diagnostic features of mesenchymal tumors of the GI tract other than gastrointestinal stromal tumor (GIST).

Molecular detection and targeting of EWSR1 fusion transcripts in soft tissue tumors

Soft tissue tumors are a heterogeneous group of tumors, traditionally classified according to morphology and histogenesis. Molecular classification divides sarcomas into two main categories: (a) sarcomas with specific genetic alterations and (b) sarcomas showing multiple complex karyotypic abnormalities without any specific pattern. Most chromosomal alterations are represented by translocations which are increasingly detected. The identification of fusion transcripts, in fact, not only support the diagnosis but also provides the basis for the development of new therapeutic strategies aimed at blocking aberrant activity of the chimeric proteins. One of the genes most susceptible to breakage/translocation in soft tissue tumors is represented by Ewing sarcoma breakpoint region 1 (EWSR1). This gene has a large number of fusion partners, mainly associated with the pathogenesis of Ewing's sarcoma but with other soft tissue tumors too. In this review, we illustrate the characteristics of this gene/protein, both in normal cellular physiology and in carcinogenesis. We describe the different fusion partners of EWSR1, the molecular pathways in which is involved and the main molecular biology techniques for the identification of fusion transcripts and for their inhibition.

Histone deacetylase inhibitors induce growth arrest, apoptosis, and differentiation in clear cell sarcoma models

Clear cell sarcoma is an aggressive malignancy occurring most commonly in the distal extremities of young adults, characterized by t(12;22)(q13;q12) creating the chimeric fusion oncoprotein EWS-ATF1. We assessed growth inhibition and differentiation effects of histone deacetylase inhibitors MS-275 and romidepsin (depsipeptide, FK228) on clear cell sarcoma cells and evaluated drug sensitivity among related translocation-associated sarcomas and other cell models. Three clear cell sarcoma cell lines, seven other sarcomas, six nonsarcoma malignant cell lines, and two nonneoplastic mesenchymal cell models were treated with MS-275 or romidepsin. Growth inhibition was assayed by monolayer 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Induction of cell cycle arrest and apoptosis were assessed by propidium iodide/Annexin V flow cytometry in monolayer and spheroid cultures and by immunoblotting analysis. Expression levels of key genes involved in mesenchymal differentiation and of EWS-ATF1 were measured by quantitative real-time PCR in clear cell sarcoma cells treated with histone deacetylase inhibitors. MS-275 and romidepsin inhibited growth in clear cell sarcoma cells by inducing cell cycle arrest and apoptosis in a time- and dose-dependent manner. Sarcomas showed greater sensitivity than other tumor types, with clear cell sarcomas most sensitive of all, whereas nonmalignant mesenchymal cells were highly resistant. MS-275 at 1 micromol/L and romidepsin at 1 nmol/L induced histone H3 acetylation, cell cycle arrest, apoptosis, and differentiation in clear cell sarcoma cells within 24 hours. Histone deacetylase inhibitors increased expression of SOX9, MYOD1, and PPARG and decreased EWS-ATF1 expression in clear cell sarcoma cells. Histone deacetylase inhibitors show promising preclinical activity in multiple clear cell sarcoma models.

Establishment and characterization of a cell line (DEOC-1) originating from a human malignant melanoma of the skin

A new human malignant melanoma cell line, designated DEOC-1, was established from the heel lesion of a 59-year-old man. This cell line has grown well for 84 months. The monolayer, cultured cells are polygonal in shape, appear to be spindle-shaped cells or multipolar cells, and have a tendency to pile up without contact inhibition. The cells are aneuploid, and the modal chromosomal number is in the hyper-triploid range. The cells were transplanted into the subcutis of SCID mice and produced tumors resembling the original tumor. The DEOC-1 cells (1 x 10(6)/5 mL) produced 5-S-cysteinyldopa (5-S-CD). The cells were not sensitive in vitro to any anticancer drug currently used for the treatment of malignant melanoma. Increases in both the protein and the transcriptional levels (mRNA) of multidrug resistance-related genes (multidrug resistance gene 1, multidrug resistance-associated protein 1 and lung resistance-related protein) were observed in DEOC-1 cells. The DEOC-1 cells are well characterized and are a very useful material for basic research of malignant melanoma.

Clear cell sarcoma of the soft parts arising in the rectus abdominis in a child - aspiration cytology of a rare case

BACKGROUND

Clear cell sarcoma of soft parts is most commonly found associated with the tendons and aponeuroses of distal extremities in young adults with a peak incidence in the third decade. Location in the abdominal wall and in a child is very rare.

CASE PRESENTATION

A nine-year-old female child presented with a swelling in the anterior abdominal wall in the suprapubic region. Fine needle aspiration revealed predominantly discrete cells with loose clustering at places. The cytoplasm was abundant, finely granular, and eosinophilic with some cells exhibiting clear vacuolated zones. No pigment was seen. The nuclei were rounded and eccentrically placed with a striking single eosinophilic macro nucleolus present in all the cells. Taking into consideration, the history, age of the patient, location of the tumor and absence of melanin pigment, a diagnosis of soft tissue sarcoma was made, the differential including Clear cell sarcoma. This was subsequently confirmed on histopathological examination and immunohistochemistry

CONCLUSION

The atypical presentation of the case made the cytological diagnosis rather challenging. Clear cell sarcoma should be considered when cytology of a soft-tissue tumor shows uncharacteristically high cellularity and relatively uniform cells with macronucleoli.

Dual-color, break-apart fluorescence in situ hybridization for EWS gene rearrangement distinguishes clear cell sarcoma of soft tissue from malignant melanoma

Clear cell sarcoma of soft tissue (malignant melanoma of soft parts) is a soft tissue sarcoma with melanocytic differentiation that typically occurs in the tendons and aponeuroses of young adults. As demonstrated by cytogenetics and reverse-transcriptase polymerase chain reaction, between 70% and over 90% of clear cell sarcomas have a t(12;22) translocation, fusing the EWS and ATF1 genes on chromosomes 22q12 and 12q13, respectively. Identification of this translocation distinguishes clear cell sarcoma from histologic mimics, most importantly conventional malignant melanoma. We report our experience with a commercially available, dual-color, break-apart fluorescence in situ hybridization (FISH) probe, which allows detection of EWS (22q12) gene rearrangement in formalin-fixed, paraffin-embedded tissues. Histologically and immunophenotypically well-characterized cases of clear cell sarcoma (n = 10) and malignant melanoma (n = 32) were evaluated with a 22q12 dual-color, break-apart probe (Vysis, Downer's Grove, IL, USA), which spans the known common breakpoints in the EWS gene on chromosome 22 (introns 7-10). Signals from tumor cell nuclei were counted under a fluorescence microscope and the presence of red-green break-apart signals was recorded. Of the clear cell sarcoma cases, seven of 10 showed evidence of an EWS gene rearrangement with a mean of 81.6% positive cells per sample (range: 60-95%). All cases of malignant melanoma (n = 32) showed virtually absent break-apart signals in the EWS gene (less than 4% cells per case). FISH detects EWS gene rearrangement in a substantial proportion of clear cell sarcomas, with excellent specificity. Importantly, EWS FISH is negative in malignant melanoma, a clinically dissimilar tumor, which may closely mimic clear cell sarcoma histologically and immunohistochemically. As the studied probe can be utilized in routinely processed tissue, FISH provides an excellent alternative to reverse-transcriptase polymerase chain reaction in cases where fresh tissue is unavailable.

Expression Profiling of t(12;22) Positive Clear Cell Sarcoma of Soft Tissue Cell Lines Reveals Characteristic Up-Regulation of Potential New Marker Genes Including ERBB3

Clear cell sarcoma of soft tissue (CCSST), also known as malignant melanoma of soft parts, represents a rare lesion of the musculoskeletal system usually affecting adolescents and young adults. CCSST is typified by a chromosomal t(12;22)(q13;q12) translocation resulting in a fusion between the Ewing sarcoma gene (EWSR1) and activating transcription factor 1 (ATF1), of which the activity in nontransformed cells is regulated by cyclic AMP. Our aim was to identify critical differentially expressed genes in CCSST tumor cells in comparison with other solid tumors affecting children and young adults to better understand signaling pathways regulating specific features of the development and progression of this tumor entity. We applied Affymetrix Human Genome U95Av2 oligonucleotide microarrays representing approximately 12,000 genes to generate the expression profiles of the CCSST cell lines GG-62, DTC-1, KAO, MST2, MST3, and Su-CC-S1 in comparison with 8 neuroblastoma, 7 Ewing tumor, and 6 osteosarcoma cell lines. Subsequent hierarchical clustering of microarray data clearly separated all four of the tumor types from each other and identified differentially expressed transcripts, which are characteristically up-regulated in CCSST. Statistical analysis revealed a group of 331 probe sets, representing approximately 300 significant (P < 0.001) differentially regulated genes, which clearly discriminated between the CCSST and other tumor samples. Besides genes that were already known to be highly expressed in CCSST, like S100A11 (S100 protein) or MITF (microphthalmia-associated transcription factor), this group shows an obvious portion of genes that are involved in cyclic AMP response or regulation, in pigmentation processes, or in neuronal structure and signaling. Comparison with other expression profile analyses on neuroectodermal childhood tumors confirms the high robustness of this strategy to characterize tumor entities based on their gene expression. We found the avian erythroblastic leukemia viral oncogene homologue 3 (ERBB3) to be one of the most dramatically up-regulated genes in CCSST. Quantitative real-time PCR and Northern blot analysis verified the mRNA abundance and confirmed the absence of the inhibitory transcript variant of this gene. The protein product of the member of the epidermal growth factor receptor family ERBB3 could be shown to be highly present in all of the CCSST cell lines investigated, as well as in 18 of 20 primary tumor biopsies. In conclusion, our data demonstrate new aspects of the phenotype and the biological behavior of CCSST and reveal ERBB3 to be a useful diagnostic marker.

The melanocyte inducing factor MITF is stably expressed in cell lines from human clear cell sarcoma

Clear cell sarcoma (CCS) is associated with the EWS/ATF1 oncogene that is created by chromosomal fusion of the Ewings Sarcoma oncogene (EWS) and the cellular transcription factor ATF1. The melanocytic character of CCS suggests that the microphthalmia-associated transcription factor (Mitf), a major inducer of melanocytic differentiation, may be miss-expressed in CCS. Accordingly, we show that the mRNA and protein of the melanocyte-specific isoform of Mitf (Mitf-M) are present in several cultured CCS cell lines (Su-ccs-1, DTC1, Kao, MST-1, MST-2 and MST-3). The above cell lines thus provide a valuable experimental resource for examining the role of Mitf-M in both CCS and melanocyte differentiation. Melanocyte-specific expression of Mitf-M is achieved via an ATF-dependent melanocyte-specific cAMP-response element in the Mitf-M promoter, and expression of Mitf-M in CCS cells suggests that EWS/ATF1 (a potent and promiscuous activator of cAMP-inducible promoters) may activate the Mitf-M promoter. Surprisingly, however, the Mitf-M promoter is not activated by EWS/ATF1 in transient assays employing CCS cells, melanocytes or nonmelanocytic cells. Thus, our results indicate that Mitf-M promoter activation may require an appropriate chromosomal context in CCS cells or alternatively that the Mitf-M promoter is not directly activated by EWS/ATF1.

Pathologic and molecular aspects of soft tissue sarcomas

This article retains the conventional approach to the classification of soft tissue sarcomas, dividing them into several major histogenetic categories based on their overall microscopic appearance, tissue differentiation pattern, and biologic potential. The author advocates a multimodal approach, in which four distinctive data sets--clinical, radiographic, microscopic, and, in some cases, molecular--are considered to establish the diagnosis and treatment plan. Such step-wise analysis is more likely to lead to consistency and accuracy as compared with an intuitive approach based on fragmentary data. The author describes individual lesions of soft tissue as clinicopathologic entities and believes that they can be more accurately diagnosed and appropriately treated with the help of data generated by a multidisciplinary team. In addition, this article emphasizes the need to use emerging molecular techniques that can provide important clues for both diagnosis and prognosis.

Establishment and characterisation of a human clear cell sarcoma model in nude mice

We have established a new experimental model of human clear cell sarcoma, UM-CCS1, using serial subcutaneous transplantation of intact tumour tissue in nude mice. The heterotransplanted nude mouse tumours retained characteristic morphological features of the primary clear cell sarcoma. Immunohistochemical analysis showed the retained expression patterns of S-100 protein, melanoma-associated antigen HMB-45 and vimentin in the xenografts as compared to the primary tumour. DNA index showed low variations both between the xenografts in the same passage and between the serial passages. Cytogenetic analysis of the primary tumour and the xenografts showed the unbalanced translocation der(6)t(6;12)(p23;q13). Based on the combined genetic data a reasonable interpretation of our findings is that there was a complex chromosomal rearrangement resulting in a cytogenetically cryptic EWS-ATF1 fusion gene. Analysis of cell kinetics using in vivo incorporation of iododeoxyuridine and flow cytometry showed generally short potential doubling time (T(pot)) of the xenografts. Volume doubling time showed low variations without correlation with T(pot). The retained phenotypic and genotypic characteristics of the primary tumour and the morphological and structural stability over time makes the model suitable for studies on the tumour biology and treatment of clear cell sarcoma.

Molecular genetic characterization of the EWS/ATF1 fusion gene in clear cell sarcoma of tendons and aponeuroses

Clear cell sarcoma (CCS) is a rare malignant soft tissue tumor particularly associated with tendons and aponeuroses. The cytogenetic hallmark is the translocation t(12;22)(q13;q12) resulting in a chimeric EWS/ATF1 gene in which the 3'-terminal part of EWS at 22q is replaced by the 3'-terminal part of ATF1 at 12q. To date, only 13 cases of CCS have been analyzed for fusion genes at the transcription level, and there is no information about the breakpoints at the genomic level. In the present study, we describe the molecular genetic characteristics of CCS from 10 patients. Karyotypes were obtained from 10 cases, 7 of which showed the characteristic t(12;22). As an initial step in the characterization of the EWS/ATF1 and ATF1/EWS chimeras, we constructed an exon/intron map of the ATF1 gene. The entire ATF1 gene spanned >40 kb and was composed of 7 exons. Intron 3, in which most of the genomic breakpoints occurred, was to a large extent (83%) composed of repetitive elements. RT-PCR amplified EWS/ATF1 cDNA fragments in all patients and ATF1/EWS cDNA fragments in 6 of 10 patients. Four types of EWS/ATF1 chimeric transcript, designated types 1-4, were identified. The most frequent chimeric transcript (type 1) was an in-frame fusion of exon 8 of EWS with exon 4 of ATF1. This was the only chimeric transcript in 5 patients but found together with other variants in 3 tumors. The type 2 transcript of EWS/ATF1, an in-frame fusion of exon 7 of EWS with exon 5 of ATF1, was detected in 4 patients, as the only transcript in 1 case and together with other variants in 3 cases. An in-frame fusion of exon 10 of EWS with exon 5 of ATF1 (type 3) was found in 1 patient as the only transcript, and an out-of-frame fusion of EWS exon 7 with ATF1 exon 7 (type 4) was detected in 1 patient together with type 1 and type 2 transcripts. Sequencing of the amplified ATF1/EWS cDNA fragments showed in 5 patients that ATF1 exon 3 was fused with EWS exon 10, resulting in an out-of-frame chimeric transcript. In 1 case, nt 428 of ATF1 (exon 4) was fused with EWS exon 8; at the junction, there was an insertion of 4 nucleotides, also resulting in an out-of-frame transcript. Genomic extra long PCR and sequence analysis mapped the genomic breakpoints to introns 7, 8 and 9 of EWS and intron 3 and exon 4 of ATF1. While a simple end-to-end fusion was observed in 2 cases, additional nucleotides were found at the junctions in 2 other cases. In addition, topoisomerase I consensus sequences were found close to the junctions, suggesting that this enzyme may participate in the genesis of the EWS/ATF1 fusion.

Newly established clear cell sarcoma (malignant melanoma of soft parts) cell line expressing melanoma-associated Melan-A antigen and overexpressing C-MYC oncogene

Clear cell sarcoma (CCS), malignant melanoma of soft parts, is a rare malignant tumor with a poor prognosis. In this study, a CCS cell line, designated MP-CCS-SY, was established from a metastatic tumor of a 17-year-old Japanese girl that originated in the left Achilles tendon. A small number of melanosomes were detected in the cytoplasm by electron microscopy. The melanosomes immunoreacted with two melanoma-associated antibodies, HMB45 and Melan-A. A Western blot demonstrated the existence of a Melan-A antigen in this cell line. Although a t(12;22)(q13;q12), which is characteristic of CCS, was not identified by a chromosomal analysis with conventional banding techniques, fluorescence in situ hybridization analysis with painting probes of chromosomes 12 and 22 revealed the insertion of a chromosome 12 fragment into one of the long arms of chromosome 22. The chimeric EWS/ATF1 transcript was detected by the reverse transcriptase polymerase chain reaction. Extra copies and structural abnormalities of chromosome 8 were observed. Overexpression of c-myc mRNA was detected by Northern blot analysis and may have a role in malignant progression of CCS. The availability of this MP-CCS-SY cell line will help to understand the molecular biology of this malignancy and should be useful as a tool for developing an immunotherapy.

Clear-cell sarcoma diagnosis by fine-needle aspiration: cytologic, histologic, and ultrastructural features; potential pitfalls; and literature review

A definitive diagnosis of clear-cell sarcoma of soft parts (CCSSP) is possible by fine-needle aspiration (FNA) biopsy alone. The aspirates are markedly cellular, consisting predominantly of discohesive cells but also of cohesive cells. The cytoplasm is eosinophilic and eccentric. The nuclei are round and contain macronucleoli. CCSSP should be considered when FNA of a soft-tissue tumor shows uncharacteristically high cellularity and relatively uniform cells with macronucleoli. Cohesion of some tumor cells does not rule out CCSSP. Melanin pigment and cytoplasmic clearing are infrequent and not necessary for the diagnosis. Sufficient material should always be procured for immunohistochemical studies on the cell block. Seven other cases are found in the literature, all correctly diagnosed by FNA. Although it is rare, CCSSP is a highly malignant tumor that can be diagnosed readily by FNA without resorting to incisional biopsy.

Clear cell sarcoma: the Roswell Park experience

BACKGROUND AND OBJECTIVES

Clear cell sarcoma of the tendons and aponeuroses (CCSTA) is an aggressive, rare soft-tissue tumor with approximately 300 reported cases. Although it appears to be histogenetically related to melanoma, its clinical behavior resembles soft tissue sarcoma with a propensity for lymph node metastases. We report our experience at a tertiary cancer center.

METHODS

Eight cases of CCSTA evaluated at Roswell Park Cancer Institute between 1970 and 1998 were reviewed retrospectively. Patient data analyzed included patient age, gender, anatomic location, size of tumor, development of local, regional and distant recurrence, and patient status at last follow up.

RESULTS

Six of eight patients were alive at 2 years, while three of seven patients were alive at 5 years. Of the patients alive with no evidence of recurrence, two had tumors of less than 2 cm, and the remaining patient had incomplete information regarding tumor size. Five patients recurred within 2 years of definitive surgical management. Four had tumors > 5 cm. All five patients progressed to metastatic disease at a median follow up of 20 months (range 1-108 months) following definitive surgical management and all eventually died of their disease at a median of 3 months (range 0-24 months) from presentation with metastatic disease. Four of five patients with lesions > 5 cm received adjuvant chemotherapy with intent to cure, but all eventually died of disease at 4, 22, 34, and 41 months from initial presentation.

CONCLUSIONS

CCSTA is an aggressive tumor of the soft tissues. Early recognition and management are associated with an excellent long-term prognosis. Tumors greater than 5 cm warrant aggressive surgical management and treatment, and are at high risk of the development of distant disease. Aggressive multiagent chemotherapy appeared to have no impact on outcome. Other adjuvant therapeutic options including immunotherapy should be investigated.

Melanotic peritoneal sarcomatosis originating from clear cell sarcoma

Peritoneal sarcomatosis was found in a 53-year-old male who had a history of resection of clear cell sarcoma (CCS) of the right wrist 7 years previously. Both the previous wrist tumor and the peritoneal disseminants consisted of small, spindle-shaped cells occasionally containing melanophages. Histologic features, histochemical demonstration of argentaffin granules, immunohistochemical reaction with HMB 45, and the demonstration of a chimeric transcript of EWS-ATF-1 established the diagnosis of CCS in the peritoneal tumors. As far as we are aware, this is the first case of a peritoneal sarcomatosis associated with CCS.

Further characterization of the human clear cell sarcoma cell line HS-MM demonstrating a specific t(12;22)(q13;q12) translocation and hybrid EWS/ATF-1 transcript

Only a small number of clear cell sarcoma (CCS) cell lines have been reported, including the cell line HS-MM. In the present study, this cell line, maintained for more than 4 years since establishment, was further characterized by cytogenetic studies, fluorescence in situ hybridization (FISH) analysis, and reverse transcriptase-polymerase chain reaction (RT-PCR). HS-MM cells both in vitro and in vivo exhibited pseudodiploid karyotypes with the specific t(12;22)(q13;q12) translocation. The translocation between chromosomes 12 and 22 was confirmed by FISH analysis and the hybrid EWS/ATF-1 transcript induced by this translocation was detected by RT-PCR. The HS-MM cell line will be useful for further studies of CCS.