Translocation t(12;22)(q13;q12.2-12.3) in a clear cell sarcoma of tendons and aponeuroses

Real-world outcomes of metastatic clear cell sarcoma sequential chemotherapy

Clear cell sarcoma is an ultra-rare chemoresistant subtype of soft tissue sarcoma. This retrospective analysis aimed to clarify the efficacy of palliative chemotherapy in CCS by assessing response rates, progression-free survival (PFS), and overall survival (OS) at a referral center. A retrospective analysis of palliative treatment was conducted on patients with CCS treated at the sarcoma unit from 1997 to 2023. Treatment responses were assessed using RECIST criteria, and the Kaplan-Meier method was used to calculate PFS and OS. The analysis covered 23 CCS chemotherapy-treated patients with 11 (47.8%) men. The median age at the palliative treatment start was 32 years (range 18-59). The median follow-up was 8.2 months. Four patients were referred to our centre for M1 disease, and 6 received perioperative chemotherapy and progressed during follow-up. In the first line, 14 patients received anthracycline-based chemotherapy (60.9%), five were treated with ifosfamide (HD-IFO), and four received other regimens. One patient (4.3%) achieved partial response (PR), and 12 patients (52.2%) achieved stable disease (SD) as the best response. Median PFS in 1 line was 2.79 months (95% CI: 2.04-8.38), and 1.76 months (95% CI: 0.72-6.97) in the second line. The median OS from first-line palliative chemotherapy was 8.2 months (95% CI: 6.2-14), and the second-line palliative chemotherapy mOS was 4.6 months (95% CI: 3.9-NA). Perioperatively anthracycline-pretreated worsened patients' median PFS in the M1 setting. Poor responses to conventional chemotherapy were observed in CCS, indicating a need for further clinical trials in this indication.

Factors associated with survival in patients with clear cell sarcoma

Aims

Clear cell sarcoma (CCS) of soft-tissue is a rare melanocytic subtype of mesenchymal malignancy. The aim of this study was to investigate the clinical and therapeutic factors associated with increased survival, stratified by clinical stage, in order to determine the optimal treatment.

Methods

The study was a retrospective analysis involving 117 patients with histologically confirmed CCS, between July 2016 and November 2017, who were enrolled in the Bone and Soft Tissue Tumour Registry in Japan.

Results

The five- and ten-year survival rates were 41% (95% confidence interval (CI) 29 to 52) and 37% (95% CI 25 to 49), respectively. On multivariable analysis, the size of the tumour of > 10 cm (p = 0.006), lymph node metastasis at the time of diagnosis (p < 0.001), distant metastases at the time of diagnosis (p < 0.001), and no surgery for the primary tumour (p = 0.019) were independently associated with a poor survival. For N0M0 CCS (n = 68), the development of distant metastases was an independent prognostic factor for survival (early (< 12 months), hazard ratio (HR) 116.78 (95% CI 11.69 to 1,166.50); p < 0.001; late (> 12 months), HR 14.79 (95% CI 1.66 to 131.63); p = 0.016); neoadjuvant/adjuvant chemotherapy (p = 0.895) and/or radiotherapy (p = 0.216) were not significantly associated with survival. The five-year cumulative incidence of local recurrence was 19% (95% CI 8 to 35) and the size of the tumour was significantly associated with an increased rate of local recurrence (p = 0.012). For N1M0 CCS (n = 18), the risk of mortality was significantly lower in patients who underwent surgery for both the primary tumour and lymph node metastases (HR 0.03 (95% CI 0.00 to 0.56); p = 0.020). For M1 CCS (n = 31), excision of the primary tumour was independently associated with better survival (HR 0.26 (95% CI 0.09 to 0.76); p = 0.013). There was no significant difference in survival between the different types of systemic treatment (p = 0.523).

Conclusion

Complete excision of the primary tumour and lymph nodes is associated with a better survival in patients with CCS. Systemic treatment appears to provide limited benefits, demonstrating a pressing need for novel systemic agents.

A rare case of primary dermal clear cell sarcoma with focal epidermotropism: An entity difficult to distinguish from melanoma

Clear cell sarcoma (CCS) is an uncommon soft-tissue sarcoma that only rarely arises within the dermis. It is challenging to distinguish dermal CCS from nodular, primary dermal, or metastatic melanoma, as they share morphologic features and immunoprofiles. We describe a dermal CCS in a 25-year-old man with a cutaneous groin mass. The lesion was initially diagnosed as melanoma, likely metastatic. On consultation, in addition to a melanoma-like tumor in the dermis, we identified focal infiltration of tumor cells into the overlying epidermis (epidermotropism), resembling primary nodular or metastatic melanoma. Given the patient's age and absence of a history of primary melanoma, fluorescence in situ hybridization (FISH) was performed, which revealed separation of the 5' and 3' EWSR1 probe signals on chromosome 22q12, prompting a diagnosis of CCS. Our case highlights the histopathological, immunohistochemical, and ultrastructural similarities between CCS and melanoma, and the consequent potential for major diagnostic confusion. In such cases, FISH analysis remains the key to diagnosis. CCS should be considered in patients with a melanoma-like tumor in the dermis or subcutaneous tissue without epidermal (or with minimal) involvement, or prior to diagnosing metastatic melanoma in the absence of a known history of primary melanoma, especially in young individuals.

Biology and management of clear cell sarcoma: state of the art and future perspectives

INTRODUCTION

Clear cell sarcoma (CCS) is an aggressive tumor, typically developing in tendons or aponeuroses. The outcome of this orphan disease is poor, with 5-year and 10-year survival rates of localized CCS around 60-70% and 40-50%. Once the disease has metastasized, it is usually fatal due to its chemotherapy-resistant nature. Systemic treatment options are poorly standardized and the use of chemotherapy is based on weak scientific evidence.

AREAS COVERED

In this review, we systematically discuss the current scientific evidence for the systemic treatment of CCS, including tyrosine kinase inhibitors, immunotherapy and MET inhibitors. Expert commentary: Recent insights in the biology of CCS have identified new potential therapeutic targets, which should be tested in prospective clinical trials. Whenever possible, patients with metastatic CCS should be included in clinical trials with good biological rationale. Innovative trial methodology and new regulatory mechanisms are required to provide patients with uncommon cancers with active drugs.

Update on Molecular Pathology of Cutaneous Melanocytic Lesions: What is New in Diagnosis and Molecular Testing for Treatment?

In this article, we give an update on recent findings regarding molecular pathology in cutaneous melanocytic tumors. The focus lies on use of genetics in the diagnosis of distinct subtypes of spitzoid tumors that are often characterized by specific phenotypic–genotypic alterations that can frequently be recognized by adequate histological examination. Typical illustrating cases are given in order to increase recognition of these lesions in daily dermatopathology practice. New molecular findings in the pathogenesis of congenital melanocytic tumors and neurocutaneous melanosis are reviewed. In addition, use of mutation analysis in the differential diagnosis of melanoma metastasis is discussed. Finally, application of mutation analysis in targeted therapy in advanced melanoma with advantages of new techniques such as next generation sequencing is described.

Identification of biomarkers to distinguish clear cell sarcoma from malignant melanoma

Clear cell sarcoma is a rare and malignant soft tissue tumor that shows phenotypic and immunohistochemical overlap with cutaneous malignant melanoma; identification of biomarkers that differentiate clear cell sarcoma from malignant melanoma is therefore needed. In this study, we performed mutation analysis of BRAF and NRAS, investigated the EWSR1 gene rearrangement and evaluated the protein expression of insulin-like growth factor 2 and insulin-like growth factor 1R in 31 cases of malignant melanoma and 16 cases of clear cell sarcoma. By direct sequencing and high-resolution melting analysis, we identified BRAF and NRAS mutations in 51.6% and 12.9% of malignant melanoma cases, respectively, while none of clear cell sarcoma harbored BRAF or NRAS mutations. Fluorescence in situ hybridization showed that 78.6% of clear cell sarcoma exhibited the t(12;22)(q13;q12) translocation. The presence of type 1, 2, and 3 EWSR1/ATF1 fusion gene transcripts was confirmed by reverse transcriptase polymerase chain reaction analysis, but type 4 and EWSR1/CREB1 fusion gene transcripts were not found. No fusion transcript could be detected in any of the malignant melanoma cases. Additionally, immunohistochemistry showed that the majority of clear cell sarcoma and malignant melanoma had insulin-like growth factor 2 and insulin-like growth factor receptor 1 expression; however the expression of insulin-like growth factor 1R was significantly higher in clear cell sarcoma compared to melanoma (p = .006). Our results suggest that the combination of BRAF and NRAS mutation analysis with fusion gene detection contributes to diagnosis of malignant melanoma and clear cell sarcoma, and that insulin-like growth factor 1R might be a novel target for the treatment of these two malignancies.

Primary clear cell sarcoma of the sacrum: a case report

Clear cell sarcoma, first described by Enzinger in 1965, is an uncommon malignant soft tissue neoplasm that displays melanocytic differentiation. It occurs predominantly in the soft tissue of the extremities in young adults or children. Primary clear cell sarcoma of the bone is extremely rare, only seven cases have been reported to our knowledge. We present here a case of a huge primary clear cell sarcoma of the sacrum arising in a 25-year-old man. The average percentage of melanin content in the tumor was 9.25 ± 6.71%, which resulted in hypointense signal in T2-weighted and heterogeneous hyperintense signal in T1-wieghted images of magnetic resonance imaging (MRI). The patient was treated with curettage of the mass and neither further radiotherapy nor chemotherapy had been provided. The patient had local regrowth of tumor at 9 months after surgery. To our knowledge, this is the first case of CCS in the axial skeleton documented in English literature.

Cutaneous clear cell sarcoma: a clinicopathologic, immunohistochemical, and molecular analysis of 12 cases emphasizing its distinction from dermal melanoma

Clear cell sarcoma (CCS) of tendons and aponeuroses/malignant melanoma (MM) of soft parts is a rare tumor and in the majority of cases presents a characteristic reciprocal translocation t(12;22)(q13;q12) that results in fusion of the EWS and ATF1 genes. Although the melanocytic differentiation of CCS is indisputable, its precise lineage remains unclear. Typically, the slowly growing tumor affects the extremities of adolescents or young adults, especially around the ankle and foot. CCS is classically regarded as a deep soft tissue tumor associated with tendons or aponeuroses. This traditional view is put into perspective by the description of primary CCS of the gastrointestinal tract that may have a variant fusion gene EWSR1-CREB1. We describe 12 cases of cutaneous CCS and discuss the differential diagnoses. These 12 cases share an identical immunohistochemical profile with MM and thus can easily be confused with a dermal variant of spindle cell MM or metastasis of MM. The patients' ages ranged from 6 to 74 years (median: 25 y), and there was a female predominance (10 females, 2 males). Most tumors (n = 9) were located on the extremities, 2 tumors arose on the back, and 1 on the abdomen. The mean tumor size was 0.97 cm (range, 0.4 to 1.7 cm). Six cases showed invasion of the subcutis, the other 6 cases were entirely dermal. Tumor necrosis was evident in 2 cases, melanin pigment in 2 cases, and ulceration in 1 tumor. All cases showed uniform nests and fascicles of pale spindled or slightly epitheloid cells with finely granular eosinophilic or clear cytoplasm. There was fair pleomorphism with plump spindled nuclei and significantly prominent nucleoli. Multinucleated wreath-like tumor giant cells were observed in two-thirds of cases, but were usually present only focally. The dense cellular aggregates were encased by delicate fibrous septa. The stroma showed a sclerotic reticulated pattern. Partly, the nests of spindle cells bordered the epidermis, prima vista mimicking junctional nests of melanocytes. The specific translocation pattern was confirmed in all cases by fluorescence in situ hybridization. Local recurrences and metastases developed in 2 and 3 patients, respectively, and 1 patient died of the disease.

Classification and pathology

Soft tissue tumors are a heterogeneous group of benign and malignant processes. Some are assumed to be reactive; others are clearly neoplastic. Because of their rarity, they frequently pose diagnostic problems for surgical pathologists. Accurate diagnosis of these tumors is enhanced by knowledge of the clinical features of the given lesions and, at times, by application of immunohistochemical and molecular techniques. In this article the lesions are described essentially in accordance with the World Health Organization classification.

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.

Myxoid clear cell sarcoma

Clear cell sarcoma is a rare soft-tissue tumor presenting typically in the extremities of young adults. It has been also known as malignant melanoma of the soft parts because of the presence of melanin and cytoplasmic melanosomes. However, clear cell sarcoma is, at present, usually considered as a unique lesion because the t(12;22)(q13;q12) translocation is present only in clear cell sarcoma. Myxoid malignant melanoma is now a well-recognized morphologic variant of malignant melanoma. However, a myxoid variant of clear cell sarcoma has not been well described yet. We report a case of myxoid clear cell sarcoma occurring on the heel in a 22-year-old man. The tumor was composed of nests and fascicles of oval to fusiform cells with clear to pale eosinophilic cytoplasm, often separated by fibrous septa. The tumor cells were reactive for S-100 protein, HMB-45, and MART-1. Variably sized cysts lined by one or several layers of tumor cells were observed. Alcian blue and mucicarmine stains demonstrated prominent mucin deposition in the tumor stroma and especially in the lumen of the cysts. Fluorescence in situ hybridization for the Ewing sarcoma gene showed rearrangement in nearly all of the neoplastic cells.

Primary clear cell sarcoma of rib

Clear cell sarcoma (malignant melanoma of soft tissues) is a very rare soft tissue neoplasm. It generally arises in tendons and aponeuroses. Although metastasis of malignant melanoma to bone is not uncommon, primary clear cell sarcoma of bone is an extremely rare neoplasm. To our knowledge five cases have been reported in the English literature. We present a case of primary clear cell sarcoma of bone in a 28-year-old woman arising in the left ninth rib. We treated the patient with total excision of the mass and postoperative radiotherapy. The patient is alive and well without local recurrence or distant metastasis at 33 months after surgery.

Alterations of the p16INK4a/p14ARF pathway in clear cell sarcoma

Clear cell sarcoma (CCS) is a very rare soft tissue sarcoma with a poor prognosis. It has become apparent through immunohistochemical, ultrastructural, and microarray analyses that CCS is a soft tissue melanocytic neoplasm. Alterations in the p16INK4a/p14ARF gene are common in malignant melanoma, which is the prototypical melanocytic neoplasm. In the present study, we performed a clinicopathologic analysis and investigated p16 and cyclin D1 expression by immunohistochemistry in 14 cases. Furthermore, we investigated genetic changes of various tumor suppressor genes and an oncogene, including p16INK4a/p14ARF, p53, beta-catenin, and APC, in 11 cases. The 5-year overall survival rate in all the patients was 33.3%. A high mitotic rate was a significant adverse prognostic factor (P = 0.004). Decreased expression of p16 was observed in 4 (28.6%) of 14 cases. Overexpression of cyclin D1 was observed in 9 cases (64.3%). SSCP analysis followed by DNA direct sequencing revealed point mutations of the p16INK4a gene in 2 of 11 cases (18.2%). In addition, one case with the p14ARF mutation and 2 cases with the p53 mutation were observed. None of the cases harbored mutation of the beta-catenin or APC gene. Homozygous deletion of the p16INK4a/p14ARF gene was detected in one case. Methylation-specific PCR did not reveal hypermethylation of the p16INK4a/p14ARF promoter region in any of the cases. Three cases harbored genetic alterations of the p16INK4a/p14ARF gene (27.3%). All tumors with genetic alterations of the p16INK4a/p14ARF or p53 gene showed a high mitotic rate or tumor necrosis. These alterations were considered to be influential in the poor prognosis of CCS patients.

Primary clear cell sarcoma of bone

Clear cell sarcoma is a rare soft tissue sarcoma of young adults with melanocytic differentiation. It occurs predominantly in the soft tissue of extremities, typically involving tendons and aponeuroses. Primary clear cell sarcoma of bone is extremely rare. We report a case of primary clear cell sarcoma of the right first metatarsal in a 48-year-old woman and provide a literature review of the entity.

Waldenström macroglobulinemia with a novel der(8;17)(q10;q10)

We report the occurrence of an unbalanced whole-arm translocation of der(8;17)(q10;q10) in an 80-year-old female patient with Waldenström macroglobulinemia. To our knowledge, der(8;17)(q10;q10) has not been described in Waldenström macroglobulinemia. Although this cytogenetic abnormality has been reported in a number of solid tumors, a literature review suggests also a possible association with B-cell chronic lymphoproliferative disorders.

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.

Suppression of p53 function in normal human mammary epithelial cells increases sensitivity to extracellular matrix-induced apoptosis

Little is known about the fate of normal human mammary epithelial cells (HMECs) that lose p53 function in the context of extracellular matrix (ECM)-derived growth and polarity signals. Retrovirally mediated expression of human papillomavirus type 16 (HPV-16) E6 and antisense oligodeoxynucleotides (ODNs) were used to suppress p53 function in HMECs as a model of early breast cancer. p53+ HMEC vector controls grew exponentially in reconstituted ECM (rECM) until day 6 and then underwent growth arrest on day 7. Ultrastructural examination of day 7 vector controls revealed acinus-like structures characteristic of normal mammary epithelium. In contrast, early passage p53- HMEC cells proliferated in rECM until day 6 but then underwent apoptosis on day 7. p53- HMEC-E6 passaged in non-rECM culture rapidly (8-10 passages), lost sensitivity to both rECM-induced growth arrest and polarity, and also developed resistance to rECM-induced apoptosis. Resistance was associated with altered expression of alpha3-integrin. Treatment of early passage p53- HMEC-E6 cells with either alpha3- or beta1-integrin function-blocking antibodies inhibited rECM-mediated growth arrest and induction of apoptosis. Our results indicate that suppression of p53 expression in HMECs by HPV-16 E6 and ODNs may sensitize cells to rECM-induced apoptosis and suggest a role for the alpha3/beta1-heterodimer in mediating apoptosis in HMECs grown in contact with rECM.

Genetic and molecular abnormalities in tumors of the bone and soft tissues

BACKGROUND

Malignant transformation requires the accumulation of multiple genetic alterations such as chromosomal abnormalities, oncogene activation, loss of tumor suppressor genes, or abnormalities in genes that control DNA repair and genomic instability. Sarcomas are a heterogeneous group of malignant mesenchymal tumors of difficult histologic classification and strong genetic predisposition. This article provides a comprehensive review of the cytogenetic abnormalities observed in bone and soft-tissue tumors, emphasizing known downstream molecular changes that may play a role in oncogenesis.

METHODS

The database of the National Library of Medicine was searched for literature relating to genetic and molecular mechanisms in sarcomas in general and in each of the main tumor entities.

RESULTS

Recent techniques in chromosome analysis and molecular cytogenetics have improved our ability to characterize genetic changes in mesenchymal tumors. Some changes are so characteristic as to be virtually pathognomonic of particular histologic types, while others are complex, difficult to characterize, and of unknown relevance to pathogenesis. The implications to the cell of some of these abnormalities are now being recognized.

CONCLUSIONS

The study of sarcomas will benefit from the information derived from genetic studies and translational research. The human genome project and new methodologies, such as computer-based DNA microarray, may help in the histogenetic classification of sarcomas and in the identification of molecular targets for therapy.

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.

Malignant melanoma is genetically distinct from clear cell sarcoma of tendons and aponeurosis (malignant melanoma of soft parts)

Clear cell sarcoma of tendons and aponeuroses (malignant melanoma of soft parts) and conventional malignant melanoma may demonstrate significant morphologic overlap at the light microscopic and ultrastructural level. Consequently, the clinically relevant distinction between primary clear cell sarcoma and metastatic melanoma in the absence of a known primary cutaneous, mucosal or ocular tumour may occasionally cause diagnostic problems. A balanced translocation, t(12;22)(q13;q13), which can be detected, amongst others, using the reverse transcriptase polymerase chain reaction (RT-PCR) or fluorescent in situ hybridization (FISH), has been identified in a high percentage (50-75%) of clear cell sarcomas and is presumed to be tumour specific. Whether this chromosomal rearrangement is present in malignant melanoma has, to date, not as yet been studied by molecular genetic or molecular cytogenetic techniques. Using RT-PCR and FISH, a series of metastases from 25 known cutaneous melanomas and 8 melanoma cell lines (5 uveal and 3 cutaneous) were screened for the t(12;22)(q13;q13) translocation. Primers for RT-PCR were chosen based upon published breakpoint sequences. The Cosmids G9 and CCS2.2, corresponding to the 5' region of EWS and 3' region of ATF-1 respectively, were used as probes. The translocation was not identified in any of the melanomas or melanoma cell lines analysed in this study; in contrast this translocation was identified in 3 out of 5 clear cell sarcomas using these techniques. This allows distinction between translocation positive cases of clear cell sarcoma and malignant melanoma at a molecular genetic level. Consequently, in diagnostically challenging cases, this represents a valuable tool for the clinicopathologic differentiation between these two entities, with an important impact on patient management and prognosis.

Microphthalmia transcription factor in the immunohistochemical diagnosis of metastatic melanoma: comparison with four other melanoma markers

The diagnosis of metastatic malignant melanoma (MMM) may be difficult in surgical pathology, often complicated by the unpredictable spread of this tumor and its great variability on histologic evaluation. Traditionally used immunohistochemical markers on melanomas are insufficient because of either a relative lack of specificity (S100 protein) or variably reported sensitivity (HMB45). Information about some newer markers, such as tyrosinase (TYR) and Melan A, is more limited. Recently, based on the study of a small number of tumors, it was suggested that microphthalmia transcription factor (MITF) is 100% sensitive in the identification of metastatic melanoma. In the current study, we compared the diagnostic usefulness of MITF with that of four other markers in 266 cases of conventional metastatic melanomas from different sites, 33 cases of desmoplastic melanomas, and 1 case of melanoma with rhabdoid features. The specificity of MITF was evaluated by using a representative sample of control tumors. Microphthalmia transcription factor with nuclear positivity was seen in 235 of 266 cases of conventional MMM (88%), usually in more than 30% of tumor cells. However, some melanomas had only foci of MITF- and TYR-positive cells, whereas the majority of cells were generally S100 protein-positive. Only 1 of 30 desmoplastic melanomas (3%) had MITF-positive cells, representing epithelioid foci resembling conventional melanoma. Two cases had TYR in a similar pattern; all were HMB45-negative. One metastatic melanoma with rhabdoid features was negative for MITF and other markers except the S100 protein. Half of the S100 protein negative conventional melanomas (6 of 12) were MITF-positive, whereas 4 of 20 (20%) TYR-negative tumors had reactivity for MITF. The percentages of positive cases of MMM (10% or more tumor cells positive) diagnosed with the four other markers in descending order were 90% (S100 protein and TYR), 78% (melan-A), and 66% (HMB45). Microphthalmia transcription factor appeared to be specific, because significant reactivity was not found in 112 carcinomas, 20 lymphomas, 20 angiosarcomas, 20 fibrous histiocytomas, and 20 malignant peripheral nerve sheath tumors. However, positive nuclei were found focally among reactive histiocytes, especially in osteoclasts, epithelioid histiocytes, and sporadic other histiocytes. Microphthalmia transcription factor may be a valuable addition to the marker panel used in diagnosing melanoma, in combination with S100, TYR, and the other markers, but it is not present in cases of desmoplastic melanomas.

Biphenotypic sarcoma with characteristics of both a Ewing sarcoma and a desmoplastic small round cell tumor

BACKGROUND

The EWS gene, a transcription factor of unknown function, is involved in chromosomal translocations associated with a wide variety of tumors, particularly small round blue cell tumors such as Ewing sarcoma. It has previously been reported that desmoplastic small round blue cell tumor (DSRBCT) frequently has an associated t(11;22) abnormality resulting from fusion of the EWS and WT-1 genes.

PROCEDURE

We report a case of a small round blue cell tumor with characteristics of both Ewing sarcoma and DSRBCT with a t(11;22) translocation leading to fusion of the EWS and FLI1genes.

RESULTS

The translocation point and fusion products were confirmed by polymerase chain reaction amplification and restriction fragment mapping of the products.

CONCLUSIONS

The biphenotypic nature of this case and the apparent promiscuity of the EWS gene in tumor-associated translocations coupled with other reports of biphenotypic childhood sarcomas has potential implications for the relationship between small round blue cell tumors and the mechanism of EWS/FLI1 oncogenesis.

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.

Clear cell sarcoma of tendons and aponeuroses (malignant melanoma of soft parts) and cutaneous melanoma: exploring the histogenetic relationship between these two clinicopathological entities

Clear cell sarcoma of tendons and aponeuroses (CCS) has come to be recognized as a distinct histopathological entity in the last three to four decades. It shares a number of histological and ultrastructural features with cutaneous melanoma (MM), occasionally creating diagnostic difficulties with metastatic melanoma in the absence of a known primary cutaneous tumour. At a genetic level, a t(12;22) has been identified in 60-75 per cent of cases of CCS using karyotype analysis, while MM demonstrates a broad range of genetic alterations, most commonly appearing to involve chromosomes 1, 5, and 6. Although these two tumour types share many common microscopic, and thus histogenetic, similarities, the genotypic evidence supports two distinct histopathological entities.

Clear cell sarcoma or malignant melanoma of soft parts: molecular analysis of microsatellite instability with clinical correlation

Malignant melanoma of soft parts, also termed clear cell sarcoma (CCS), is a rare malignancy of neural crest origin which is different from cutaneous malignant melanoma. Although a translocation involving chromosomes 12 and 22 is characteristic of clear cell sarcoma and not malignant melanoma, there are a paucity of methods to differentiate the two. Therefore, a study of microsatellite instability (MIN) was undertaken to determine if mechanisms of DNA mismatch repair can differentiate these malignancies. MIN has been described in a variety of malignancies including 25% of malignant melanomas. Paraffin-embedded neoplastic and non-neoplastic cells were obtained from 11 individuals (five males; six females; age range from seven to 60 years) with CCS. Isolated DNA was PCR amplified at 17 separate microsatellite loci using radioactive-labeled primers. Tumor tissue was compared to normal tissue for each analysis. No MIN was detected. Loss of heterozygosity was detected in only one patient at a single locus (IFNA). The lack of MIN in clear cell sarcoma further defines the distinction between this tumor and malignant melanoma. Clinically, local recurrence and metastasis were indicators of poor outcome. The size of the tumor was not a significant prognostic indicator. Local recurrence, satellitosis, or nodal metastasis was not proven to be uniformly fatal. Utilization of chemotherapy and/or radiation demonstrated no obvious survival advantage. The histologic parameters of mitotic rate and the presence of necrosis were not prognostic. Limb-preserving surgical procedures were as effective as amputation for local disease control. The actuarial survival rate was calculated to be 48% at five years.

Clear cell sarcoma of tendons and aponeuroses with t(12;22) (q13;q12) diagnosed initially as malignant melanoma

Cytogenetic analysis performed on a specimen from an inguinal lymph node metastasis of a tumor diagnosed initially as a cutaneous malignant melanoma revealed the following karyotype: 50,XX, +2, +7, +8, +8, t(12;22) (q13;q12). The finding of t(12;22) (q13;q12), an abnormality specific of clear cell sarcoma of tendons and aponeuroses (CCS), prompted reanalysis of histologic slides, and a final diagnosis of CCS was made. Our case illustrates the usefulness of cytogenetic analysis in the differential diagnosis of CCS and malignant melanoma. In addition, extra copies of chromosomes 8, 7, and 2, present in our case as well as in previously reported tumors, seem to play an important, although at present not understood, role in the development of CCS.

Molecular biological aspects of soft tissue tumors

In the preceding, the reader has hopefully developed an appreciation of the major malignant tumors to be encountered in somatic soft tissues in children, adolescents, and young adults. In aggregate, this group of tumors accounts for about 20% of cancer in this age group. Importantly, they are curable tumors when nonmetastatic at presentation, but therapy appropriate to prognosis and tumor responsiveness is highly dependent on precise diagnosis. The historical morphologic methods alone will not suffice for this purpose, but the anticipated rapid advent of molecular genetic diagnostic and prognostic methods should. Useful, practical, and rapid genetic tests, available in the same time frame as the routine histopathologic evaluation of these tumors, are likely to forever change the diagnosis and management of these tumors, individually and as a group.

Band 11q13 is nonrandomly rearranged in hibernomas

Cytogenetic study of a short-term culture from a hibernoma, a very rare benign proliferation of the brown fat, demonstrated a four-break translocation t(5;7;11;17)(p14;q11.23;q13.1-13.3;p11.2) as the sole abnormality in all analyzed cells. Complex translocation involving band 11q13 have also been detected in the two other published cases of hibernoma. The consistent finding of 11q13 rearrangements appears to distinguish hibernoma from other benign adipose tissue tumors cytogenetically and suggests that 11q13 changes may play an important role in hibernoma pathogenesis.

Aberrations of chromosome 22 and polysomy of chromosome 8 as non-random changes in clear cell sarcoma

Cytogenetic analysis was performed on a primary tumor and a metastatic lesion of a clear cell sarcoma of tendons and aponeuroses (CCS), a rare soft tissue neoplasm of uncertain histopathologic origin. Clonal chromosomal abnormalities resulting in two related clones were found in both tumors. The karyotype was near-triploid with several structural and numerical changes, comprising a der(15;22) (q10;q10). Including the present case, 14 of 15 cases of CCS have had structural or numerical aberrations of chromosome 22 and nine of them (65%) displayed a similar or identical t(12;22)(q13-14;q12-13). Our findings suggest that in the absence of specific t(12;22), other abnormalities of chromosome 22 may be significant. In addition, increased doses of chromosome 8 found in 70% of the tumors strongly suggest a significant role for this chromosome in the development of clear cell sarcoma.