[Granular CALLA-positive acute lymphoblastic leukemia]

One of the main criteria in the differentiation between acute lymphoblastic (ALL) and acute myeloblastic leukemias (AML) is the presence of granules in the blasts of the latter. Recently, several groups have described a form of ALL with prominent intracytoplasmatic granules (G-ALL) in the blasts. The granules in the G-ALL blasts do not contain myeloperoxidase, but sometimes have lipids that stain with Sudan black B (SBB). We describe a case of G-ALL in a five-year-old girl whose peripheral blood and bone marrow was compound of 98% lymphoblasts, 30% of which, had prominent azurophilic intracytoplasmatic granules. The granules did not have peroxidase, acid phosphatase, varies; is directly proportional to naphthyl acetate esterase. However 5% of the blasts had sudanophilic granules and 60% were positive for the periodic acid-Schiff reaction. The blasts expressed the CD10 (CALLA) and Dr antigens, and were negative for surface immunoglobulins or the CD4, CD8, or CD14, antigens. Only 18% of cells formed rosettes with sheep erythrocytes. The patient responded to vincristine, prednisone and L-asparaginase. Based on the finding we diagnosed this as a CALLA positive G-ALL. By conventional criteria this case would have been wrongly classified as AML.