MALIGNANT-MELANOMA OF THE SOFT PARTS (CLEAR-CELL SARCOMA) - CONFIRMATION OF EWS AND ATF-1 GENE FUSION CAUSED BY A T(12-22) TRANSLOCATION

We report on the cytogenetic and molecular analysis of a malignant mel anoma of the sob parts (MMSP). A t(12;22)(q13;q12) was found as the on ly structural chromosomal change, and this provides additional support for the important role of this translocation in MMSP development. Mol ecular analysis revealed in frame fusion between exon 10 of the Ewing' s sarcoma oncogene (EWS) and codon 110 of ATF-1. In previously analyze d MMSPs, junctions were observed between EWS exon 8 and ATE-I codon 65 . The present data thus indicate that, as in Ewing's sarcoma, differen t fusion proteins can occur in MMSP. The presence of the EWS/ATF-1 fus ion gene in the tumor cells was demonstrated by dual color fluorescenc e in situ hybridization on interphase nuclei. Our data provide additio nal support for the specific association of the t(12;22) and the resul ting EWS/ATF-1 gene fusion in MMSP. This particular genetic aberration , therefore, serves as a strong diagnostic marker for MMSP. We conclud e that detection of the t(12;22) by cytogenetic or molecular analysis is useful in establishing or confirming the diagnosis of MMSP.