Acute leukemic transformation of myelodysplastic syndrome: Is cytochemistry still relevant?

Abstract

This case was a diagnostic challenge. The monoblasts had unusual morphology with some resembling proerythroblasts and others closer to dysplastic myeloblasts/promyelocytes, although neither the shape nor granulation was typical of either. On the original bone marrow aspirate they were difficult to identify as being of myeloid lineage as myeloperoxidase was negative (despite the cytoplasmic granules) and no blast population was identifiable by immunophenotyping. Although the cytological features were not typical for monoblasts and the blast count was <20%, if ANBE had been performed on the original bone marrow aspirate, the monoblasts would have been correctly identified. This would have saved a considerable amount of additional testing although management may not have been altered. This case demonstrates the ongoing utility of cytochemical staining, a technique that has been replaced in many laboratories by immunophenotyping. Cytochemistry remains necessary to assist in the diagnosis of acute myeloid leukemia, not otherwise specified, as well as in other myeloid neoplasms where the positive identification of monocytic cells is relevant. It is a rapid and easy test that is still relevant in the modern hematology laboratory. Nothing to report.