IgA multiple myeloma coexistent with atypical adult T-cell leukemia.

We report a 65-yr-old male with adult T-cell leukemia (ATL) who developed multiple myeloma (MM) concomitantly. Skin lesions and peripheral leukocytosis were noted during the 5-yr observation period. There was abnormal lymphocytosis with indented or lobulated nuclei in the peripheral blood and in the bone marrow. The neoplastic cells reacted with monoclonal antibodies, OKT3, OKT4, OKIa1 and anti-Tac. His serum was positive for the antibodies to ATL-associated antigens. Human T-cell leukemia virus (HTLV) proviral DNA was detected in the leukemic cells. Thus, a diagnosis of ATL was made. There was IgA (k) paraprotein in his serum, and Bence-Jones protein (k) in urine samples. Fine needle aspiration revealed pathologic flaming plasma cells. Multiple osteolytic lesions appeared on his skull 5 yr after the initial examination. Thus, a diagnosis of MM concomitant with ATL was made.