Abstract
The term โbasophilic leukemiaโ has been in use for 75 years. However, consistent diagnostic criteria are lacking. This is due to the rarity of the disease and to the routine unavailability of special tests that are often required to confirm a diagnosis. We report an unusual case of acute basophilic leukemia in a child who was referred to our Center, arriving with partially treated acute lymphoblastic leukemia. Basophilic differentiation on light microscopy was evident from the coarse basophilic granules in blasts, a progressive maturation of blasts toward basophils, and toluidine positivity on cytochemistry. Blasts showed a myeloid immunophenotype (CD13^+^, CD33^+^, CD117^+^) with a characteristic dual positivity for CD34 and CD25, highly suggestive of basophilic nature of the blasts. Conventional cytogenetic studies revealed translocation t(8;21)(q22;q22). A diagnosis of acute basophilic leukemia with t(8;21) was made. Review of preโtherapy slides showed features consistent with AMLโM2 with basophilia. There were no basophilic blasts. With these features, a diagnosis of acute basophilic leukemia secondary to AMLโM2 was made. In our patient, basophilic leukemia appears to have evolved from selective clonal proliferation of โbasophilโcommitted blastsโ during the course of the disease in a case of AMLโM2 with basophilia. Am. J. Hematol. 76:134โ138, 2004. ยฉ 2004 WileyโLiss, Inc.