Diagnostic utility of EWS break-apart fluorescence in situ hybridization in distinguishing between non-cutaneous melanoma and clear cell sarcoma.
Clear cell sarcoma (CCS) is a rare soft tissue sarcoma with morphological similarities to malignant melanoma (MM), but with a distinct genetic background that includes the chromosomal translocation t(12;22)(q13;q12). Clear cell sarcoma is often misdiagnosed as MM because of similarities in target locations and immunophenotypes. Eighteen cases with MM in non-cutaneous sites were subjected to fluorescence in situ hybridization (FISH) to assess EWS gene breakage. Tissue microarrays were constructed using formalin-fixed, paraffin-embedded tissue and the EWSR1 (22q12) dual-color, break-apart rearrangement probe (Vysis) was used. Two patients were classified as CCS with EWS gene rearrangement, with a mean of 67.5% positive cells per sample according to break-apart FISH. The remaining 16 patients lacked break-apart signals of the EWS gene. The presence of type 1 (EWS exon 8-ATF1 exon 4) fusion transcripts was confirmed in FISH-positive patients by RT-PCR. Retrospective analysis revealed that the masses were located in the foot and buttock, respectively. Morphologically, tumor cells were not typical for those of CCS or MM. Break-apart FISH is an accurate and convenient method for differentiating between MM and CCS. Molecular detection of EWS gene rearrangement, either by break-apart FISH or RT-PCR, is mandatory in subjects with melanotic tumors of soft tissue.
Song
Joon Seon
JS
Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Songpa-gu, Seoul, Korea.
Choi
Jene
J
Kim
Ji Hun
JH
Jang
Se Jin
SJ
Cho
Kyung-Ja
KJ
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005091:Exons / Q000235:genetics; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000235:genetics; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D034802:RNA-Binding Protein EWS / Q000235:genetics*; D012189:Retrospective Studies; D018227:Sarcoma, Clear Cell / Q000175:diagnosis* / Q000235:genetics; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000235:genetics; D014178:Translocation, Genetic / Q000235:genetics
D034802:RNA-Binding Protein EWS