IMMUNOREACTIVITY FOR A103, AN ANTIBODY TO MELAN-A (MART-1), IN ADRENOCORTICAL AND OTHER STEROID TUMORS

The Melan-A (MART-1) gene encodes an antigen recognized by cytotoxic T cells. It has been said to be restricted in its expression to melanoc ytes. However, here we report the presence of immunoreactivity for A10 3, an antibody to Melan-A, in five adrenocortical adenomas, 16 primary and 13 metastatic adrenocortical carcinomas, four Leydig cell tumors of the testis, and three Sertoli-Leydig cell tumors of the ovary. To e valuate the potential diagnostic role of this antibody, we studied imm unoreactivity for A103 in 111 carcinomas, 40 germ cell tumors, and 33 miscellaneous nonmelanocytic epithelioid tumors. All of them were nega tive for A103. Our findings suggest that once melanoma is excluded, A1 03 can aid in the recognition of steroid hormone-producing tumors and may be particularly useful in the diagnosis of adrenocortical carcinom a. The presence of immunoreactivity for A103 practically excludes any other carcinoma that may enter into the differential diagnosis of adre nocortical tumors.