Clear cell sarcoma of the ileum: the crucial role of cytogenetics for the diagnosis.

We report a case of clear cell sarcoma that arose in the ileum and metastasized to the liver. The tumor cells did not contain melanin or glycogen; expressed S-100 protein, but not HMB45; and contained possible atypical melanosomes when examined by electron microscopy. They carried a clonal chromosomal rearrangement: 50,XY,t(2;7)(q37;q22),+8,+8,+9,+11, t(12;22)(q13;q12). The diagnosis was greatly facilitated by the cytogenetic analysis. The translocation t(12;22)(q13;q12-13) has been reported as specific for clear cell sarcomas.