Atypical blasts and bone marrow necrosis associated with near-triploid relapse of acute promyelocytic leukemia after arsenic trioxide treatment.

The pathologic features of acute promyelocytic leukemia (APL) with t(15;17)(q22;q21) are highly characteristic, which with few exceptions enable a firm diagnosis to be made on morphologic grounds. An APL patient in first relapse presented with large, bizarre circulating blasts and bone marrow necrosis 2 weeks after chemotherapy consolidation for an arsenic trioxide-induced remission. Although a morphologic diagnosis could not be reached, cytogenetic investigations showed a near-triploid clone with t(15;17), confirming APL in second relapse. This case showed that clonal evolution with additional karyotypic aberrations might alter the blast morphology and pathologic features in APL. Copyright 2002, Elsevier Science (USA). All rights reserved.