Cytogenetic comparison between clear cell sarcoma and a case of acral clear cell melanoma

Clear cell melanoma is a recently described variant of melanoma characterized by prominent clear cell features similar to clear cell sarcoma.

The present report describes a deeply invasive case of clear cell melanoma clinically, histologically, immunohistochemically, ultrastructurally and with the FISH technique and compares these findings with those in clear cell sarcoma.

A 68-year-old male presented with an ulcerated, deeply invasive melanoma on the heel, corresponding to Clark level V, with a maximum tumour thickness of more than 14 mm; follow-up revealed inguinal lymph-node and lung metastases. Apart from characteristic histological features of melanoma with intraepidermal involvement, the lesion was immunohistochemically positive for 5100 protein, with HMB45 and A103 (anti-human Melan-A/MART-1), and ultrastructurally showed melanosomes. In deeply invasive parts, the lesion was indistinguishable from clear cell sarcoma, exhibiting nests, fascicles and sheets of pale-staining epithelioid to spindle-shaped cells ('clear cells') with scattered Touton-like multinucleated giant cells. Cytogenetic analysis using the FISH technique revealed a 12q13 chromosomal break in the vicinity of the ATFI gene but without ATF1 disruption.

These findings may indicate the possible involvement of the ATF1 gene in clear cell melanoma tumorigenesis, similar to clear cell sarcoma with classical t(12;22) translocation.