PLASMA-CELL LEUKEMIA MIMICKING ACUTE MONOCYTIC LEUKEMIA IN THE COURSEOF MULTIPLE-MYELOMA

We report a case of acute leukaemia occurring early in the course of I gA multiple myeloma. Ultrastructural studies, immunophenotyping and ka ryotyping were required to identify the origin and clonality of the le ukaemic cells. Although ultrastructural examination of the blast cells revealed both monocytoid and plasma cell features, all cells expresse d the CD 38 antigen and intracytoplasmic kappa light chains, while kar yotyping revealed a clone with numerous abnormalities, leading to the diagnosis of clonal plasma cell disease. The occurrence of leukaemia i n multiple myeloma is discussed.