An acute myeloid leukemia M6b blast crisis with giant proerythroblasts in chronic myeloid leukemia.

The case of a 12 yr old female with bcr-abl positive chronic myeloid leukemia who subsequently developed a fatal AML-M6b (pure erythroleukemia) blast crisis is presented. The case is unique for its rarity of occurrence and for the striking resemblance that the circulating proerythroblasts showed to the giant cells characteristically seen in Parvovirus B19-induced acute pure red cell aplasia. This is, to the best of our knowledge, the first description of such cells in a blast crisis of chronic myeloid leukemia.