HMB-45-positive malignant lymphoma. A case report with literature review of aberrant HMB-45 reactivity.

The monoclonal antibody HMB-45 is a highly specific and sensitive marker of malignant melanoma. Rarely, however, aberrant reactivity to nonmelanocytic tumors has been observed. We report an immunoblastic lymphoma of B-cell phenotype that reacted with HMB-45 in a 70-year-old white woman. To our knowledge, this is the first report of HMB-45-positive malignant lymphoma (excluding plasmacytoma). Of an additional 13 cases of benign and malignant lymphoid tissue, only benign plasma cells in one case reacted with HMB-45.