Acute basophilic leukemia. A case report.

A case of acute nonlymphocytic leukemia (ANLL) with primitive basophilic differentiation is presented. The patient had no antecedent history or concomitant presence of chronic myelogenous leukemia. The leukemic blasts constituted 83% of the peripheral white blood cells and more than 90% of the marrow nucleated cells. Cytoplasmic vacuoles were found in some leukemic cells. About half the leukemic cells showed a few azurophilic granules stained with Wright's stain, whereas exhibited a faint pinkish hue around the cells without cytoplasmic granules (water-soluble granules) by Riu's stain. The cytoplasmic granules failed to be stained with peroxidase but stained positively with toluidine blue. The former result could lead one to misclassify the case as lymphoid leukemia, but the characteristic finding of basophilic cells in Riu's stain should direct one to make the diagnosis of ANLL with basophilic differentiation. The cytochemical findings of this case suggested that basophilic differentiation should be considered when leukemic cells show peroxidase-negative granules. Riu's stain and toluidine blue stain are useful to make the correct diagnosis.