[Overt leukemia from MDS associated with marked basophilia].

A 52-year-old woman was admitted to our hospital because of leukocytosis. She had been diagnosed with RAEB in another hospital in past time. At the admission, the white cell count was 30,900/microliter with blasts (14.0%) and marked basophilia (49.0%). Bone marrow aspiration revealed with 30.2% blasts and 21.1% basophils. Having obtained those results, diagnosis of RAEB in transformation was made. After admission, number of basophils in peripheral blood increased gradually, and level of histamine in serum was elevated significantly. Multiple peptic ulcers in stomach and bowel and high fever were induced due to histaminemia. Despite several therapy she died because of respiratory failure and septisemia. Although the mechanism of basophilia in this patient could not be clarified, there was a possibility that basophilia in this patient might be differentiated from leukemic clone because almost basophils in peripheral blood were mature and those had many granules including metachromasia by stained with toluidine blue.