Blast cell leukemia with IgM monoclonal gammopathy and intracytoplasmic vacuoles and Auer-body-like inclusions.

A patient with acute leukemia and an IgM, kappa (IgMkappa) monoclonal gammopathy, Bence-Jones proteinuria, and blasts containing intracytoplasmic vacuoles with peroxidase-positive inclusions is discussed. Special stains, immunofluorescence, and electron microscopy suggested that the vacuoles were autophagosomes containing Auer-body-like inclusions, and that the blast cells did not synthesize the paraprotein. Chemotherapy with cyclophosphamide, vincristine, and prednisone resulted in transient improvement of the leukemia, but the level of the paraprotein was unchanged. Other case reports involving monoclonal gammopathy in association with acute leukemia are reviewed and contrasted with this case.