Diagnosis of clear cell sarcoma by real-time reverse transcriptase-polymerase chain reaction analysis of paraffin embedded tissues

Essential role of postoperative follow-up in the management of clear cell sarcoma

Clear cell sarcoma (CCS) is a rare melanocytic soft tissue sarcoma known for its propensity to metastasize to the lymph nodes and typically has an unfavorable prognosis. Currently, surgical resection is the primary treatment for localized CCS, while radiotherapy and chemotherapy are preferred for metastatic cases. The roles of adjuvant chemotherapy, radiotherapy, and lymph node dissection are controversial. Although immunotherapy has emerged as a promising avenue in CCS treatment research, there are no established clinical standards for postoperative follow-up. This editorial discusses a recent article by Liu et al, with a focus on current diagnostic modalities, treatment approaches, and the challenging prognosis associated with CCS. Our aim is to underscore the importance of long-term patient follow-up in CCS management.

The Impact of Expert Pathology Review and Molecular Diagnostics on the Management of Sarcoma Patients: A Prospective Study of the Hellenic Group of Sarcomas and Rare Cancers

Precise classification of sarcomas is crucial to optimal clinical management. In this prospective, multicenter, observational study within the Hellenic Group of Sarcoma and Rare Cancers (HGSRC), we assessed the effect of expert pathology review, coupled with the application of molecular diagnostics, on the diagnosis and management of sarcoma patients. Newly diagnosed sarcoma patients were addressed by their physicians to one of the two sarcoma pathologists of HGSRC for histopathological diagnostic assessment. RNA next-generation sequencing was performed on all samples using a platform targeting 86 sarcoma gene fusions. Additional molecular methods were performed in the opinion of the expert pathologist. Therefore, the expert pathologist provided a final diagnosis based on the histopathological findings and, when necessary, molecular tests. In total, 128 specimens from 122 patients were assessed. Among the 119 cases in which there was a preliminary diagnosis by a non-sarcoma pathologist, there were 37 modifications in diagnosis (31.1%) by the sarcoma pathologist, resulting in 17 (14.2%) modifications in management. Among the 110 cases in which molecular tests were performed, there were 29 modifications in diagnosis (26.4%) through the genomic results, resulting in 12 (10.9%) modifications in management. Our study confirms that expert pathology review is of utmost importance for optimal sarcoma diagnosis and management and should be assisted by molecular methods in selected cases.

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.

The current management of clear cell sarcoma

Clear cell sarcoma (CCS) is a rare melanocytic soft tissue sarcoma with a high propensity for lymphatic metastasis and poor prognosis. It is characterized by the translocation of t (12;22), resulting in the rearrangement of the EWSR1 gene and overexpression of MET. Despite improvements in the diagnosis and treatment of soft tissue sarcomas, the management of CCSs remains challenging owing to their rarity, unique biological behaviour and limited understanding of their molecular pathogenesis. The standard treatment for localized CCSs is surgical excision with negative margins. However, there is an ongoing debate regarding the role of adjuvant chemotherapy, radiotherapy and lymphadenectomy in the management of this disease. CCSs are usually resistant to conventional chemotherapy. Targeted therapies, such as sunitinib and MET inhibitors, may provide promising results. Immunotherapy, particularly immune checkpoint inhibitors, is currently under investigation as a potential treatment option for CCSs. Further research is needed to better understand the biology of CCSs and develop effective therapeutic strategies. The purpose of this review is to provide a comprehensive overview of current knowledge and advances in the diagnosis and treatment of CCSs.

Primary Clear Cell Sarcoma of Bone: Clinicopathologic Study of a Rare Presentation

Clear cell sarcoma (CCS) is an uncommon malignant mesenchymal neoplasm of young adults with a predilection for tendons and aponeuroses of distal extremities, a distinctive nested growth pattern, melanocytic differentiation, and usually an EWSR1::ATF1 fusion. Distinction from melanoma can be challenging but is critical for clinical management. Rare cases of primary bone CCS have been reported. The purpose of this study was to evaluate the clinicopathologic features of a series of primary bone CCS. Three cases of primary bone CCS were identified out of 140 CCS diagnosed between 2010 and 2021. Two patients were female, and 1 patient was male; ages were 19, 47, and 61 years. All tumors arose in the long bones of the extremities (femur, humerus, fibula). Two tumors also involved regional lymph nodes at presentation. Two showed characteristic histologic features, in the form of nests and fascicles of uniform epithelioid to spindle cells with prominent nucleoli and pale eosinophilic to clear cytoplasm; 1 tumor showed sheet-like growth, unusual focal pleomorphism, and more notable nuclear atypia. By immunohistochemistry, S100 protein was positive in 2/3 cases, SOX10 in 3/3, HMB-45 in 2/3, MiTF in 2/2, and melan A in 1/3. All cases were confirmed to harbor EWSR1 rearrangement and EWSR1::ATF1 fusion or t(12;22). On follow-up, all 3 patients developed metastases and died of disease, 5, 18, and 21 months after diagnosis. In summary, CCS rarely presents in the skeleton. At such locations, distinction from metastatic melanoma is particularly challenging. Clinical and pathologic features are similar to conventional CCS of soft tissue. Primary bone CCS may pursue an aggressive clinical course.

Comprehensive genomic profiling of EWSR1/FUS::CREB translocation-associated tumors uncovers prognostically significant recurrent genetic alterations and methylation-transcriptional correlates

To elucidate the mechanisms underlying the divergent clinicopathologic spectrum of EWSR1/FUS::CREB translocation-associated tumors, we performed a comprehensive genomic analysis of fusion transcript variants, recurrent genetic alterations (mutations, copy number alterations), gene expression, and methylation profiles across a large cohort of tumor types. The distribution of the EWSR1/FUS fusion partners-ATF1, CREB1, and CREM-and exon involvement was significantly different across different tumor types. Our targeted sequencing showed that secondary genetic events are associated with tumor type rather than fusion type. Of the 39 cases that underwent targeted NGS testing, 18 (46%) had secondary OncoKB mutations or copy number alterations (29 secondary genetic events in total), of which 15 (52%) were recurrent. Secondary recurrent, but mutually exclusive, TERT promoter and CDKN2A mutations were identified only in clear cell sarcoma (CCS) and associated with worse overall survival. CDKN2A/B homozygous deletions were recurrent in angiomatoid fibrous histiocytoma (AFH) and restricted to metastatic cases. mRNA upregulation of MITF, CDH19, PARVB, and PFKP was found in CCS, compared to AFH, and correlated with a hypomethylated profile. In contrast, S100A4 and XAF1 were differentially upregulated and hypomethylated in AFH but not CCS. Unsupervised clustering of methylation profiles revealed that CREB family translocation-associated tumors form neighboring but tight, distinct clusters. A sarcoma methylation classifier was able to accurately match 100% of CCS cases to the correct methylation class; however, it was suboptimal when applied to other histologies. In conclusion, our comprehensive genomic profiling of EWSR1/FUS::CREB translocation-associated tumors uncovered mostly histotype, rather than fusion-type associated correlations in transcript variants, prognostically significant secondary genetic alterations, and gene expression and methylation patterns.

Primary clear cell sarcoma of soft tissue in the posterior cervical spine invading the medulla oblongata: A case report

BACKGROUND

Clear cell sarcoma (CCS) is a rare and highly malignant soft tissue tumor, usually occurring in the deep soft tissues of the distal tendons and aponeurosis of the extremities, especially the feet and knees. CCS originating in the head and neck is extremely rare. The clinical manifestations of CCS in the head and neck are not typical, and the imaging manifestations have certain characteristics, but the diagnosis still depends on pathological examination and genetic testing.

CASE SUMMARY

A 33-year-old male patient had paroxysmal headache for more than 4 years, accompanied by nausea and vomiting, which could be relieved after rest. Computed tomography angiography showed a left paraspinal soft tissue mass. Contrast-enhanced imaging showed obvious uneven enhancement with adjacent bone lytic destruction. Magnetic resonance imaging examination showed isosignal on T₁-weighted images, slightly high signal on T₂-weighted images (T₂WI), high signal on Tirm fat suppression sequence, significantly high signal on diffusion weighted imaging, and obvious and uneven enhancement. The lesion invaded the anterior medulla oblongata through the left atlantoaxial foramen and compressed the cervical spinal cord on T₂WI. Primary CCS of soft tissue was diagnosed by pathology and genetic examination.

CONCLUSION

CCS should be considered in the differential diagnosis of soft tissue tumors of the head and neck, and their diagnosis depends on pathological examination and genetic testing.

EWSR1-The Most Common Rearranged Gene in Soft Tissue Lesions, Which Also Occurs in Different Bone Lesions: An Updated Review

EWSR1 belongs to the FET family of RNA-binding proteins including also Fused in Sarcoma (FUS), and TATA-box binding protein Associated Factor 15 (TAF15). As consequence of the multifunctional role of EWSR1 leading to a high frequency of transcription of the chromosomal region where the gene is located, EWSR1 is exposed to aberrations such as rearrangements. Consecutive binding to other genes leads to chimeric proteins inducing oncogenesis. The other TET family members are homologous. With the advent of widely used modern molecular techniques during the last decades, it has become obvious that EWSR1 is involved in the development of diverse benign and malignant tumors with mesenchymal, neuroectodermal, and epithelial/myoepithelial features. As oncogenic transformation mediated by EWSR1-fusion proteins leads to such diverse tumor types, there must be a selection on the multipotent stem cell level. In this review, we will focus on the wide variety of soft tissue and bone entities, including benign and malignant lesions, harboring EWSR1 rearrangement. Fusion gene analysis is the diagnostic gold standard in most of these tumors. We present clinicopathologic, immunohistochemical, and molecular features and discuss differential diagnoses.

Primary clear cell sarcoma of the femur: a unique case with RT-PCR and direct sequencing confirmation of EWSR1/ATF1 fusion gene

Background

It is very rare for clear cell sarcomas (CCS) to arise in the bone. During diagnosis, it is important to distinguish primary CCS of bone from bone metastasis of melanoma because this difference fundamentally changes the therapeutic options. Recently, characteristic fusion genes of CCS have been detected using reverse transcription polymerase chain reaction (RT-PCR) or direct sequencing which allowed to distinguish CCS from melanoma. However, there was no study applying these analyses with positive results. In this case, we describe the use of fusion gene analysis to diagnose a primary CCS of the bone.

Case presentation

A 36-year-old male presented with a four-months history of left knee pain. Magnetic resonance imaging showed a lesion in the left femoral medial epicondyle. Histological examination of the biopsy specimen revealed proliferating oval or rounded cells. These cells had clear cytoplasm arranged in fascicles or compact nests with frequent deposits of brown pigment. Furthermore, immunohistochemistry analysis revealed that tumor cells were positive for S-100 protein, HMB-45, Melan-A, and SOX10. It stained negative for CD34 and BRAF v600e. Conclusively, detection of the EWSR1/ATF1 fusion gene using RT-PCR and direct sequencing confirmed that the lesion was a primary CCS of the bone. Wide-margin resection and reconstruction with a tumor endoprosthesis were performed.

Conclusions

Herein, we diagnosed a rare case of primary CCS of the bone by detecting EWSR1/ATF1 fusion gene using RT-PCR and direct sequencing. Since fluorescence-in situ hybridization (FISH) and RT-PCR could show false positive by mainly due to technical problems, it is better to perform direct sequencing to confidently diagnose the tumor as a primary CCS especially at very rare site such as bone.

Primary Intracranial Mesenchymal Tumor with EWSR1-CREM Gene Fusion: A Case Report and Literature Review

BACKGROUND

The prevalence of gene translocation in some mesenchymal tumors can be used as highly specific molecular diagnostic markers in clinic and pathology. EWSR1 is a partner gene in a large, diverse range of mesenchymal tumors.

CASE DESCRIPTION

This paper describes the case of a 31-year-old man who was diagnosed with a primary intracranial mesenchymal tumor with EWSR1-CREM gene fusion and eventually returned to a normal live with no signs of tumor recurrence or metastasis after treatment, including surgery therapy, radiotherapy, and 6 cycles of vincristine-doxorubicin-cyclophosphamide chemotherapy, even though the classification and grade of the tumor are still controversial.

CONCLUSIONS

This case is a novel entity of intracranial mesenchymal neoplasm with EWSR1-CREM gene fusion which was confirmed by histopathology, molecular pathology, and next-generation sequencing (NGS). The literature review shows only 5 cases of intracranial tumor harboring EWSR1-CREM gene fusion with similar features. With the further application of molecular pathology and NGS in clinical practice, there will be more intracranial mesenchymal tumor cases with EWSR1-CREM gene fusion found in the future, which may lead to further understanding of the diagnosis and clinical features of this neoplasm.

Primary Cutaneous Clear Cell Sarcoma, Clinical Outcome With Sentinel Lymph Nodes Status

OBJECTIVES

Primary cutaneous clear cell sarcoma (PCS) is a rare malignancy and difficult to differentiate from melanoma. We investigated factors influencing survival and recurrence.

METHODS

An institutional cancer registry and literature search were used for a retrospective study. Only clear cell sarcoma cases with a primary site of skin and subcutaneous tissue were included. Kaplan-Meier and Cox regression analyses were used to assess survival time and hazard ratios.

RESULTS

Three eligible cases were identified at our institution. In addition, the PubMed and Google Scholar reviews identified 1,878 items, with 23 patients with PCS. The median age was 25 years with 62% female. The tumors ranged in size from 0.4 to 4.5 cm. Cytogenetics showed t(12;22)(q13;q12) in all cases and a unique variant of t(2;22)(q32.3;q12) in one case. Surgery was the most common treatment, followed by chemotherapy/radiation. PCS recurred in 46% of patients with a median relapse-free survival time of 15 months. Only two known PCS-related mortalities were recorded, at 38 and 60 months following initial diagnosis. Smaller tumor size and negative sentinel lymph node biopsy (SLNB) status were significantly associated with a better disease-free survival.

CONCLUSIONS

Tumor size and SLNB status influence PCS survival and recurrence. More research is needed due to the rarity of this disease.

Clear Cell Sarcoma of the Foot in an 18-Year-Old Female

We report a case of an 18-year-old female without a relevant medical history who presented with an 8-month history of a left foot mass. It started as a small nodule that progressively increased in size over time. The mass then became ulcerative with foul-smelling discharge. There was no palpable left inguinal or other lymph nodes upon physical examination. Histological examination of the biopsy confirmed a diagnosis of clear cell sarcoma. Clear cell sarcoma is a rare soft tissue neoplasm. However, early diagnosis is crucial to prevent metastasis and worsened prognosis. Clear cell sarcoma has an extremely poor prognosis once metastasis occurs, and to the best of our knowledge, only fewer than 100 cases have been reported in the literature.

Mesenchymal Tumors with EWSR1 Gene Rearrangements

Among the various genes that can be rearranged in soft tissue neoplasms associated with nonrandom chromosomal translocations, EWSR1 is the most frequent one to partner with other genes to generate recurrent fusion genes. This leads to a spectrum of clinically and pathologically diverse mesenchymal and nonmesenchymal neoplasms, variably manifesting as small round cell, spindle cell, clear cell or adipocytic tumors, or tumors with distinctive myxoid stroma. This review summarizes the growing list of mesenchymal neoplasms that are associated with EWSR1 gene rearrangements.

Primary clear cell sarcoma of the tongue and surgical reconstruction: About a rare case report

Clear cell sarcomas (SCC), also called "soft-tissue melanoma", are rare and aggressive tumors that preferentially affect the lower limbs (tendons and fasciae) and which have also been described in head and neck localizations. Their clinical and immunohistochemical mimicry with melanoma makes it difficult to diagnose sarcomas. SCC treatment is mainly focused on large-scale resection surgery with adjuvant radiotherapy because of their low chemo-sensitivity and extreme lymphophilia. In case of head and neck localization, these treatments may lead to function and aesthetic sequelae thus requiring the use of modern techniques of reconstructive surgery. The authors describe the diagnosis, treatment and follow-up of large lingual SCC case using a DIEP free flap reconstruction according to an original technique developed in the department. Given the characteristics of patients with SCC (a high proportion of women between 20 and 40 years old) and its inherent qualities (low morbidity of the donor site, volume delivered and excellent plasticity), the fascio-cutaneous free flap type "DIEP" "taken according to the design of the" Cathedral triptych seems to be a viable choice among the range of reconstruction solutions.

Clear cell sarcoma of the gastrointestinal tract and malignant gastrointestinal neuroectodermal tumour: distinct or related entities? A review

Clear cell sarcoma is an uncommon sarcoma which rarely occurs as a primary tumour in the gastrointestinal tract (CCS-GIT). It shares common molecular genetic abnormalities with the more recently described entity, malignant gastrointestinal neuroectodermal tumour (GNET) but is distinguished by its morphological and immunohistochemical findings. The exact nosological relationship between these tumours continues to be debated. In this review, we present two cases of these rare neoplasms from our files and perform a statistical comparison of all published cases to determine if significant differences exist in their clinicopathological features and biological behaviour. Thirteen cases of CCS-GIT and 58 of GNET were included. CCS-GIT occurred more commonly in males (84.6% vs 46.6%, p = 0.01) and in an older age group (median 57 vs 33 years, p < 0.01). There was no significant difference in their location in the gastrointestinal tract, median tumour size and proportion of cases with an EWSR1-ATF1 vs EWSR1-CREB1 fusion. Median survival for CCS-GIT was 13.5 months and for GNET, 9.5 months (p = 0.78). There was no significant difference in the Kaplan-Meier survival curves for either time to first metastasis (p = 0.88) or overall survival (p = 0.18), including after controlling for tumour size using regression models. Our analysis confirms that aside from morphological variations between these tumours, they also exhibit epidemiological and clinical differences. Despite the prevalent perception that GNET is associated with a more aggressive clinical course, our findings indicate that there is no significant difference in their biological behaviour, although both clearly share a bleak prognosis. Further experience is awaited to determine optimal treatment strategies and whether CCS-GIT and GNET would differ in their response to various therapies.

USP6 activation in nodular fasciitis by promoter-swapping gene fusions

Nodular fasciitis is a self-limited myofibroblastic lesion that can be misdiagnosed as a sarcoma as a result of its rapid growth, cellularity, and sometimes prominent mitotic activity. A recurrent translocation t(17;22) has been identified in nodular fasciitis, fusing the coding region of USP6 to the promoter region of MYH9, and resulting in increased USP6 expression. A subset of cases show USP6 rearrangement without the typical fusion variants by RT-PCR, or any MYH9 rearrangement by FISH. We sought to further characterize such tumors using molecular diagnostic assays. A novel RT-PCR assay was designed to detect the two known MYH9-USP6 fusion types in formalin-fixed paraffin-embedded and frozen tissue, and a break-apart FISH assay was designed to detect USP6 rearrangement. Twenty-six cases of nodular fasciitis diagnosed between 2002 and 2013 were retrieved from the pathology files of our institutions and were confirmed to be positive by FISH and/or RT-PCR. Seven samples showed USP6 rearrangement by FISH but were negative for MYH9-USP6 fusion by RT-PCR; these cases were subjected to a next-generation sequencing assay utilizing anchored multiplex PCR technology. This assay targets a single partner gene associated with fusions in bone and soft tissue tumors for agnostic detection of gene fusion partners. Novel fusion partners were identified in all seven cases and confirmed by RT-PCR. Structurally, all fusions consisted of the juxtaposition of the entire coding region of USP6 with the promoter of the partner gene, driving increased USP6 expression. This study confirms the neoplastic nature of nodular fasciitis, defines additional pathogenic fusion partners, and adds to the growing body of literature on USP6-associated neoplasia. Given the diagnostic challenges of these tumors, molecular assays can be useful ancillary tools; however, the prevalence of promoter swapping must be recognized when interpreting results.

Soft Tissue Tumors of Uncertain Histogenesis: A Review for Dermatopathologists

The mesenchymal tumors discussed herein represent a heterogeneous group of neoplasms with distinctive morphologic, immunophenotypic, and molecular genetic features. These uncommon tumors often arise in the dermis and subcutis and can pose a major diagnostic challenge to dermatopathologists because they closely mimic melanoma, carcinoma, fibrous histiocytoma, schwannoma, or granulomatous inflammation. This article reviews the clinical presentation, histopathology, differential diagnosis, and diagnostic pitfalls of epithelioid sarcoma, clear cell sarcoma, perivascular epithelioid cell tumor, ossifying fibromyxoid tumor, pleomorphic hyalinizing angiectatic tumor, and hemosiderotic fibrolipomatous tumor. Associated molecular genetic findings are also briefly reviewed with an emphasis on their diagnostic usefulness.

Advances in the Genetic Characterization of Cutaneous Mesenchymal Neoplasms: Implications for Tumor Classification and Novel Diagnostic Markers

Cutaneous mesenchymal neoplasms often pose significant diagnostic challenges; many such entities are rare or show clinical and histologic overlap with both other mesenchymal and non-mesenchymal lesions. Recent advances in the genetic classification of many cutaneous mesenchymal neoplasms have not only helped define unique pathologic entities and increase our understanding of their biology, but have also provided new diagnostic markers. This review details these recent discoveries, with a focus on their implications for tumor classification and diagnosis.

The spectrum of EWSR1-rearranged neoplasms at a tertiary sarcoma centre; assessing 772 tumour specimens and the value of current ancillary molecular diagnostic modalities

Background:

EWSR1 rearrangements were first identified in Ewing sarcoma, but the spectrum of EWSR1-rearranged neoplasms now includes many soft tissue tumour subtypes including desmoplastic small round cell tumour (DSRCT), myxoid liposarcoma (MLPS), extraskeletal myxoid chondrosarcoma (EMC), angiomatoid fibrous histiocytoma (AFH), clear cell sarcoma (CCS) and myoepithelial neoplasms. We analysed the spectrum of EWSR1-rearranged soft tissue neoplasms at our tertiary sarcoma centre, by assessing ancillary molecular diagnostic modalities identifying EWSR1-rearranged tumours and reviewing the results in light of our current knowledge of these and other Ewing sarcoma-like neoplasms.

Methods:

We retrospectively analysed all specimens tested for EWSR1 rearrangements by fluorescence in situ hybridisation (FISH) and/or reverse transcription–PCR (RT–PCR) over a 7-year period.

Results:

There was a total of 772 specimens. FISH was performed more often than RT–PCR (n=753, 97.5% vs n=445, 57.6%). In total, 210 (27.9%) specimens were FISH-positive for EWSR1 rearrangement compared to 111 (14.4%) that showed EWSR1 fusion transcripts with RT–PCR. Failure rates for FISH and RT–PCR were 2.5% and 18.0%. Of 109 round cell tumours with pathology consistent with Ewing sarcoma, 15 (13.8 %) cases were FISH-positive without an identifiable EWSR1 fusion transcript, 4 (3.7%) were FISH-negative but RT–PCR positive and 4 (3.7%) were negative for both. FISH positivity for DSRCT, MLPS, EMC, AFH and CCS was 86.3%, 4.3%, 58.5%, 60.0% and 87.9%, respectively. A positive FISH result led to diagnostic change in 40 (19.0%) EWSR1-rearranged cases. 13 FISH-positive cases remained unclassifiable.

Conclusions:

FISH is more sensitive for identifying EWSR1 rearrangements than RT–PCR. However, there can be significant morphologic and immunohistochemical overlap between groups of EWSR1-rearranged neoplasms, with important prognostic and therapeutic implications. FISH and RT–PCR should be used as complementary modalities in diagnosing EWSR1-rearranged neoplasms, but as tumour groups harbouring EWSR1 rearrangements are increasingly characterised and because given translocations involving EWSR1 and its partner genes are not always specific for tumour types, it is critical that these are evaluated by specialist soft tissue surgical pathologists noting the morphologic and immunohistochemical context. As RT–PCR using commercial primers is limited to only the most prevalent EWSR1 fusion transcripts, the incorporation of high-throughput sequencing technologies into the standard diagnostic repertoire to assess for multiple molecular abnormalities of soft tissue tumours in parallel (including detection of newly characterised Ewing sarcoma-like tumours) might be the most effective and efficient means of ancillary diagnosis in future.

Primary clear cell sarcoma of the head and neck: a case series with review of the literature

BACKGROUND

Clear cell sarcoma typically arises in deep soft tissues of the foot/ankle. Primary head and neck clear cell sarcoma is rare. We report three molecularly confirmed primary head and neck clear cell sarcoma and review the literature.

METHODS

Head and neck clear cell sarcoma with no primary elsewhere were retrieved from archival/consultation files. English language literature review of all reported head and neck clear cell sarcoma was performed.

RESULTS

Three cases were identified. The tumors, all in men, presented on the scalp of a 33-year-old, face of a 20-year-old and tongue of a 44-year-old. Tumors ranged from 0.6 to 1.4 cm. All had typical features of clear cell sarcoma, including nests of tumor cells divided by fibrous septae. One had multinucleated wreath-like giant cells. One had a focal junctional component. Immunohistochemistry was positive for S100 (three out of three), HMB45 (three out of three) and Melan-A (two out of three). All had EWSR1 rearrangements by fluorescence in situ hybridization. Follow up available for one patient revealed no evidence of disease after wide excision and radiation. Seven additional reported cases were identified and tabulated.

CONCLUSION

Head and neck clear cell sarcoma is rare but should be considered in the differential diagnosis of nested tumors with fibrous septae. Molecular analysis should be considered for definitive diagnosis regardless of location.

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.

Clinical effect of molecular methods in sarcoma diagnosis (GENSARC): a prospective, multicentre, observational study

BACKGROUND

Advances in molecular genetics of sarcoma have enabled the identification of type-specific aberrations. We aimed to assess the clinical effect of systematic implementation of molecular assays to improve sarcoma misdiagnosis.

METHODS

In this multicentre, observational study, we recruited patients from 32 centres of the French Sarcoma Group/Reference Network in Pathology of Sarcomas. Eligibility criteria included: biopsy or surgical resection; suspicion of: dermatofibrosarcoma protuberans (cohort 1), dedifferentiated liposarcoma (cohort 2), Ewing's sarcoma family of tumours (cohort 3), synovial sarcoma (cohort 4), alveolar rhabdomyosarcoma (cohort 5), and myxoid or round cell liposarcoma (cohort 6); review by one sarcoma-expert pathologist; availability of frozen material (except for cohort 1 of patients with dermatofibrosarcoma protuberans because anti-CD34 immunohistochemistry is performed on paraffin-embedded tissue); and patient information. For each case, the pathologist made one primary diagnosis followed by up to two differential diagnoses, based on histological characteristics only. Each diagnosis was classified as certain, probable, or possible. For each case to determine the molecular classification, we did fluorescence in-situ hybridisation on paraffin-embedded samples. We also did comparative genomic hybridisation and quantitative PCR (cohort 2) or reverse transcriptase PCR (cohorts 3-6) on frozen and paraffin-embedded samples. We made a final diagnosis based on the molecular results. The clinical effect of diagnosis correction was assessed by a board of experts.

FINDING

Between June 22, 2009, and Oct 30, 2012, 395 patients were enrolled in the study, of which 384 were eligible for inclusion. The diagnosis was eventually modified by molecular genetics for 53 patients: eight (16%) of 50 patients with dermatofibrosarcoma (cohort 1), seven (23%) of 30 patients with dedifferentiated liposarcoma (cohort 2), 13 (12%) of 112 with Ewing's sarcoma family of tumours (cohort 3), 16 (16%) of 97 patients with synovial sarcoma (cohort 4), seven (15%) of 46 patients with alveolar rhabdomyosarcoma (cohort 5), and two (4%) of 49 patients with myxoid or round cell liposarcoma (cohort 6), with an effect on primary management or prognosis assessment in 45 cases.

INTERPRETATION

Molecular genetic testing should be mandatory for diagnostic accuracy of sarcoma and appropriate clinical management, even when histological diagnosis is made by pathologist experts in this field.

FUNDING

French National Cancer Institute and Nice University Hospital.

Gross examination and reporting of soft tissue tumours: evaluation of compliance with the UK Royal College of Pathologists soft tissue sarcoma dataset

Aims

Soft tissue tumours are a heterogeneous group of neoplasms that can arise at almost every anatomical site. As they often show similar clinical and radiological findings, histology is the definitive diagnostic method and it is crucial that the surgical pathology report contains accurate, useful information for management and prognostication. The soft tissue sarcoma minimum dataset produced by the Royal College of Pathologists in the UK outlines a structure for handling and reporting soft tissue tumours, including the core data required, and aiding pathologists in forming a consistent reporting approach.

Methods

We assessed the information in surgical pathology reports for soft tissue lesions at a tertiary soft tissue centre, in 1 year prior to the development of this dataset, and 1 year after its release, to audit the comparative adequacy of macroscopic and microscopic information provided, and to assess for differences in reporting since the advent of routine ancillary molecular diagnostic testing.

Results and conclusions

We found that while essential information was always included in reports, more specific details contributing to better quality reports such as more detailed macroscopic descriptions and a higher proportion of clinical summaries with radiological correlation were included in 2011 than 2006, despite increasing workload. Specimen handling, particularly of core biopsies, was also improved, reflecting the increasing need to conserve the maximum amount of patient material for molecular investigations.

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.

Non-antiepileptic drugs for trigeminal neuralgia

BACKGROUND

Trigeminal neuralgia was defined by the International Association for the Study of Pain as a sudden, usually unilateral, severe, brief, stabbing recurrent pain in the distribution of one or more branches of the fifth cranial nerve. Standard treatment is with anti-epileptic drugs. Non-antiepileptic drugs have been used in the management of trigeminal neuralgia since the 1970s. This is an update of a review first published in 2006 and previously updated in 2011.

OBJECTIVES

To systematically review the efficacy and tolerability of non-antiepileptic drugs for trigeminal neuralgia.

SEARCH METHODS

On 20 May 2013, for this updated review, we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL (2013, Issue 4), MEDLINE (January 1966 to May 2013), EMBASE (January 1980 to May 2013), LILACS (January 1982 to May 2013) and the Chinese Biomedical Retrieval System (1978 to May 2013). We searched clinical trials registries for ongoing trials.

SELECTION CRITERIA

We included double-blind, randomised controlled trials in which the active drug was used either alone or in combination with other non-antiepileptic drugs for at least two weeks.

DATA COLLECTION AND ANALYSIS

Two authors decided which trials fitted the inclusion criteria and independently graded risk of bias. We assessed the quality of the evidence according to the GRADE criteria for this update.

MAIN RESULTS

In this 2013 update, we updated the searches, but identified only two new ongoing studies. The review includes four trials involving 139 participants. The primary outcome measure in each was pain relief. Three trials compared one of the oral non-antiepileptic drugs tizanidine, tocainide or pimozide with carbamazepine. The quality of evidence for all outcomes for which data were available was low. In a trial of tizanidine involving 12 participants (one dropped out due to unrelated disease), one of five participants treated with tizanidine and four of six treated with carbamazepine improved (risk ratio (RR) 0.30, 95% confidence interval (CI) 0.05 to 1.89). Few side effects were noted with tizanidine. For pimozide, there was evidence of greater efficacy than carbamazepine at six weeks. Up to 83% of participants reported adverse effects but these did not lead to withdrawal; the report did not provide comparable data for carbamazepine. Limited data meant that we could not assess the effects of tocainide; however, data from non-randomised studies (not included in this review) indicate that serious haematological adverse events can occur. A trial involving 47 participants compared 0.5% proparacaine hydrochloride eyedrops with placebo but did not show any significant benefits, again according to low-quality evidence. The report did not mention adverse events. The proparacaine trial was at low risk of bias; the other trials were at unclear risk of bias overall.

AUTHORS' CONCLUSIONS

There is low-quality evidence that the effect of tizanidine is not significantly different than that of carbamazepine in treating trigeminal neuralgia. Pimozide is more effective than carbamazepine, although the evidence is of low quality and the data did not allow comparison of adverse event rates. There is also low-quality evidence that 0.5% proparacaine hydrochloride eye drops have no benefit over placebo. Limitations in the data for tocainide prevent any conclusions being drawn. There is insufficient evidence from randomised controlled trials to show significant benefit from non-antiepileptic drugs in trigeminal neuralgia. More research is needed.

Clear cell sarcoma of the jaw: a case report and review of the literature

Clear cell sarcoma (CSS) is a unique malignant soft tissue tumor that mainly occurs from the aponeurotic tissue and tendons of extremities. It is rare in the pediatric population. The tumor does not respond well to chemotherapy or irradiation. Complete surgical resection offers the best chance for a cure. Most studies have demonstrated poor prognosis of this tumor, if it is >5 cm. The literature suggests that local recurrence and distant metastasis are not uncommon even with wide resection and that late recurrence and metastasis commonly occur. This case report discusses CSS in the jaw of a pediatric patient. To our knowledge, this is the only case of CSS of the jaw.

Molecular diagnostics complementing morphology in superficial mesenchymal tumors

Molecular techniques are increasingly important in the practice of surgical pathology. In soft tissue tumors, there are a number of tumors with recurring cytogenetic abnormalities. Knowledge of these abnormalities has furthered our understanding of these tumors and has also allowed development of molecular techniques to aid in the diagnosis. This review will focus on mesenchymal tumors with specific cytogenetic abnormalities that may present as a superficial tumor of the dermis or subcutis.

Cutaneous neoplasms showing EWSR1 rearrangement

Rearrangements of the EWSR1 gene are found in an increasing number of human neoplasms, including several tumors that can involve the skin: Ewing sarcoma/primitive neuroectodermal tumor, angiomatoid (malignant) fibrous histiocytoma, myoepithelioma of soft tissue, and clear cell sarcoma. Although these tumors share this common genetic link, they have very different clinical features, morphology, immunophenotype, and sometimes fusion gene partners; these will be the subjects of this review.

Molecular Pathology of Sarcoma

The rapid growth of tissue-based molecular pathology has changed the practice of the surgical pathologist signing out soft tissue tumors. This information is presented in a practical and succinct manner focusing on clinically validated findings that have diagnostic or therapeutic relevance. The approach is morphologically based and focuses on differential diagnoses and clinical scenarios. Molecular techniques can be an invaluable ancillary tool.

Tumors with EWSR1-CREB1 and EWSR1-ATF1 fusions: the current status

EWSR1-CREB1 and EWSR1-ATF1 are gene fusions of which one or both have now been consistently described in 5 histopathologically and behaviorally diverse neoplasms: angiomatoid fibrous histiocytoma, conventional clear cell sarcoma (of tendons and aponeuroses), clear cell sarcoma-like tumor of the gastrointestinal tract, hyalinizing clear cell carcinoma of the salivary gland, and primary pulmonary myxoid sarcoma. Some of the tumors in this group have been described only recently, and others have been the subject of recent genetic insights contributing to their characterization. These neoplasms are all rare; yet, the increasing frequency with which EWSR1-CREB1 and EWSR1-ATF1 fusions are being described in separate entities is noteworthy. The additional molecular mechanisms by which tumors with such variable morphologic, immunohistochemical, and clinical phenotypes are generated are yet to be understood. We review the clinicopathologic and molecular features of this group of neoplasms unified by the presence of EWSR1-CREB1 and EWSR1-ATF1 genetic fusions.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Primary pulmonary myxoid sarcoma with EWSR1-CREB1 fusion: a new tumor entity

We present clinicopathologic data on 10 pulmonary myxoid sarcomas, which are defined by distinctive histomorphologic features and characterized by a recurrent fusion gene, that appear to represent a distinct tumor entity at this site. The patients [7 female, 3 male; aged 27 to 67 y (mean, 45 y)] presented with local or systemic symptoms (n=5), symptoms from cerebral metastasis (1), or incidentally (2). Follow-up of 6 patients showed that 1 with brain metastasis died shortly after primary tumor resection, 1 developed a renal metastasis but is alive and well, and 4 are disease free after 1 to 15 years. All tumors involved pulmonary parenchyma, with a predominant endobronchial component in 8 and ranged from 1.5 to 4 cm. Microscopically, they were lobulated and composed of cords of polygonal, spindle, or stellate cells within myxoid stroma, morphologically reminiscent of extraskeletal myxoid chondrosarcoma. Four cases showed no or minimal atypia, 6 showed focal pleomorphism, and 5 had necrosis. Mitotic indices varied, with most tumors not exceeding 5/10 high-power fields. Tumors were immunoreactive for only vimentin and weakly focal for epithelial membrane antigen. Of 9 tumors, 7 were shown to harbor a specific EWSR1-CREB1 fusion by reverse transcription-polymerase chain reaction and direct sequencing, with 7 of 10 showing EWSR1 rearrangement by fluorescence in situ hybridization. This gene fusion has been described previously in 2 histologically and behaviorally different sarcomas: clear cell sarcoma-like tumors of the gastrointestinal tract and angiomatoid fibrous histiocytomas; however, this is a novel finding in tumors with the morphology we describe and that occur in the pulmonary region.

Clear-cell sarcoma of the soft tissue--a rare diagnosis with a fatal outcome

Clear-cell sarcomas account for less than 1% of all soft tissue tumours. They most often occur in middle-aged adults as a deeply located lesion with predilection to the tendons and aponeuroses. The aim of the present study was to show possible influencing factors on the outcome after surgical treatment in a detailed case series. We reviewed the medical records of 11 patients with the diagnosis of a clear-cell sarcoma of the soft tissue. These cases were analysed with regard to age, gender, localisation, tumour size, recurrence free survival and overall survival. A minimum follow up of 12 months was achieved. The mean age at the point of diagnosis was 47.9 years. Metastases occurred after a mean of 19.2 months. In the cases with a tumour diameter >5 cm, metastases occurred earlier. When treated in a specialist centre, metastases occurred later. Patients died a mean of 18.4 months after developing metastatic disease. Patients with tumour size >5 cm at the point of primary diagnosis died earlier than patients with a tumour size <5 cm. It is important to detect clear-cell sarcomas as soon as possible and the final surgical treatment should be performed in a centre familiar with the treatment of soft tissue tumours not only to prolong overall survival, but also to treat the patient in a multiprofessional team.

Racial differences in the incidence of mesenchymal tumors associated with EWSR1 translocation

BACKGROUND

The incidence of Ewing sarcoma varies by race, with very low rates among persons of African and East Asian ancestry. The incidence by race of other mesenchymal tumors that also harbor EWSR1 translocations has not been studied.

METHODS

The SEER database was queried to find cases of mesenchymal tumors associated with EWSR1 translocations: Ewing sarcoma; clear cell sarcoma; extraskeletal myxoid chondrosarcoma; myxoid liposarcoma; desmoplastic small round cell tumor; and myoepithelial tumor. Age-adjusted incidence rates were calculated for white, African American, and Asian/Native American populations and compared statistically.

RESULTS

Ewing sarcoma was significantly less common in the African American and Asian/Native American populations compared with the white population, with incidence rate ratios of 0.12 (95% CI, 0.08-0.20; P<0.001) and 0.54 (95% CI, 0.41-0.69; P<0.001), respectively. Desmoplastic small round cell tumor was significantly more common in the African American population compared with the white population (incidence rate ratio=3.0; 95% CI, 1.62-5.49; P<0.001). Myxoid liposarcoma was significantly less common in the Asian/Native American population compared with the white population (incidence rate ratio=0.72; 95% CI, 0.56-0.92; P=0.006). The incidence rates for extraskeletal myxoid chondrosarcoma, myoepithelial tumors, and clear cell sarcoma did not differ significantly by race.

CONCLUSIONS

Tumors associated with EWSR1 translocation are not uniformly more common in people of European ancestry.

IMPACT

The relationship between race and EWSR1 somatic translocation is complex. Future studies investigating the genetic epidemiology of EWSR1 translocated tumors are required.

Utilization of fluorescence in situ hybridization in the diagnosis of 230 mesenchymal neoplasms: an institutional experience

CONTEXT

Mesenchymal neoplasms harbor characteristic translocations and amplification of gene regions amenable to evaluation by fluorescence in situ hybridization (FISH).

OBJECTIVE

To determine the utility of FISH in the diagnosis of mesenchymal neoplasms.

DESIGN

Two hundred thirty soft tissue cases analyzed by FISH were reviewed retrospectively.

RESULTS

Morphologic patterns where FISH was used included high-grade round cell sarcomas (n  =  67), nonmyogenic spindle cell sarcomas (n  =  40), low-grade myxoid neoplasms (n  =  34), adipocytic neoplasms (n  =  20), and melanocytic neoplasms (n  =  19). Fifty cases did not fit into the previously mentioned categories. SYT FISH (96% of monophasic synovial sarcomas were positive; 0% of malignant peripheral nerve sheath tumor were positive) and DDIT3 FISH (100% of myxoid/round cell liposarcomas; no other neoplasm positive) were very sensitive and specific. EWSR1 FISH was very sensitive and specific in the differential diagnosis of melanocytic neoplasms (88% of clear cell sarcomas were positive; all melanomas were negative). EWSR1 FISH was sensitive among high-grade round cell sarcomas (positive in 100% of desmoplastic small round cell tumors and 96% of Ewing sarcoma/primitive neuroectodermal tumors) but not specific because clear cell sarcoma, extraskeletal myxoid chondrosarcoma, and a subset of round cell liposarcomas also harbor rearrangements of EWSR1. FUS FISH was very sensitive in detecting low-grade fibromyxoid sarcomas (91% positive) but not specific because most myxoid/round cell liposarcomas also contain rearrangements of FUS. All atypical lipomatous tumors were positive for amplification of MDM2, whereas all lipomas were negative. FOXO1A FISH was positive in ∼70% of cases of alveolar rhabdomyosarcoma.

CONCLUSION

FISH is a useful adjunct in the diagnosis of mesenchymal neoplasms.

Clear cell sarcoma of tendons and aponeuroses, and osteoclast-rich tumour of the gastrointestinal tract with features resembling clear cell sarcoma of soft parts: a review and update

Clear cell sarcoma (CCS) is a rare, distinctive soft tissue neoplasm, typically occurring in the distal extremities of young adult patients. Although CCS shows melanocytic differentiation, it is now clear that it is clinicopathologically and genetically distinct from conventional malignant melanoma. The 'osteoclast-rich tumour of the gastrointestinal tract with features resembling clear cell sarcoma of soft parts' is an extraordinarily rare gastrointestinal neoplasm that shares some features of CCS, but differs from it in other ways. The historical, histopathological, ultrastructural, immunohistochemical and genetic aspects of these two tumours are reviewed in this article.

Small blue round cell tumor of the interosseous membrane bearing a t(2;22)(q34;q12)/EWS-CREB1 translocation: a case report

Background

The group of small blue round cell tumors encompasses a heterogeneous group of neoplasms characterized by primitive appearing round cells with few distinguishing histologic features.

Results

We report the case of a small blue round cell tumor with an EWS gene rearrangement detected by fluorescent in situ hybridization (FISH) analysis that mimicked Ewing sarcoma, but with unusual histology and immunohistochemical features. Multi-color karyotyping identified the presence of a t(2;22)(q34;q12) that was initially expected to represent a variant EWSR1-FEV translocation. After an extensive workup, the lesion is considered to represent a clear cell sarcoma harboring an EWSR1-CREB1 fusion transcript.

Conclusions

This case appears to represent a rare variant of clear cell sarcoma arising in peripheral soft tissues with unusual histology and unique immunophenotype. In this circumstance, FISH for all EWSR1 translocation partners or RT- PCR for a spectrum of possible transcript variants is critically important for diagnosis, since cytogenetic analysis or clinical FISH assay using only commercial EWSR1 probes will be misleading.

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.

Fluorescence in situ hybridization in the diagnosis of soft tissue neoplasms: a review

This paper presents an overview of the role of fluorescence in situ hybridization (FISH) in the diagnosis of soft tissue neoplasms. Many soft tissue neoplasms harbor characteristic translocations or amplification of gene regions, which can be assessed by FISH, and can be used to assist in their diagnosis. We discuss the major morphologic categories in which FISH has come to be used including high-grade round cell sarcomas, spindle cell sarcomas, low-grade myxoid neoplasms, adipocytic neoplasms, and malignant melanocytic neoplasms on the basis of a recent review of soft tissue neoplasms which were analyzed by FISH. We also review the molecular alterations (translocations and amplification of gene regions), which have come to define many of these diagnostic entities and the most effective way to evaluate them with FISH with attention to potential pitfalls. Finally, we discuss the advantages and disadvantages of FISH as a technique when appraising soft tissue neoplasms.

Primary dermal melanoma: A case report and molecular characterization

Swetter et al. proposed primary dermal melanoma (PDM) as a distinct entity based on an excellent prognosis. The histopathological features of PDM are extremely similar to those of metastatic melanoma or clear cell sarcoma (CCS). We describe a 38-year-old woman with a subcutaneous tumor in her left thigh. Physical and imaging examinations showed no evidence of metastatic melanoma. The lesion showed obvious strong expression of KIT by immunohistochemistry, but no EWS-ATF1 fusion transcript specific for CCS was detected by reverse transcription polymerase chain reaction. In further analyses of KIT expression in other tumors, three of four primary melanomas (75%) and six of 12 metastatic melanomas (50%) were moderately or strongly positive, however, both the primary and metastatic lesions of CCS tested negative. We believe this to be a case of PDM, and emphasize the distinctiveness of PDM.