Abnormal Granulopoiesis of Leukemic Cells with Basophil/Mast Cell Features Cytochemical and Ultrastructural Observations

<jats:p>We have carried out cytochemical and ultrastructural examination of human leukemic cells showing basophil/mast cell features derived from patients with acute myelogenous leukemia or basophilic crisis in chronic myelogenous leukemia. Leukemic cells in each case initially showed meta‐chromasia with toluidine blue and various degrees of positivity for astra blue. Other cytochemical results showed considerable variety among cases. The number of granules increased in short‐term culture in every case. Ultrastructurally, small membrane‐bound granules with or without myelinoid bodies or glycogen particles were present in immature blasts, followed by production of other granule types. In some cases, leukemic cells before and after liquid culture contained the typical basophil granules with or without myelinoid bodies, but the matrix was more loose than normal. Granules showing whorl or scroll matrix profiles, which were typical for mast cells, were present in two cases. In one case, immatue leukemic cells contained theta granules, and some mature forms after short term culture contained typical basophil/mast cell granules as well as theta granules. Leukemic cells occasionally contained multivesicular granules predominantly. These results indicate that leukemic cells with basophil/ mast cell features show a heterogeneous configuration and contain abnormal granules differing from normal ones. This abnormal granulopoiesis may be attributable to the results of leukemic events and may be a hallmark for recognition of leukemic basophils/mast cells. Acta Pathol Jpn 41: 531–539, 1991.</jats:p>