A 56-year-old female with multiple myeloma, IgG-κ type, obtained a complete remission after a combination chemotherapy with vincristine, cyclophosphamide, methyl-CCNU and prednisolone. Thirty one months after initial diagnosis when she was still in complete remission, she was found to have orbital tumor. Three months later, a breast tumor developed. A resected specimen showed poorly differentiated plasmacytoma. Immunoperoxidase stains revealed IgG-κ protein in the cytoplasm of the tumor cells. The orbital tumor disappeared after addition of melphalan to the above mentioned protocol. Several months later, intra- and extraskeletal tumors developed in various sites successively. In spite of temporary response to the radiotherapy and intensive chemotherapy, she died two months after leukemic conversion.
