ACUTE PROMYELOCYTIC LEUKEMIA WITH THE PSEUDO-CHEDIAK-HIGASHI ANOMALY AND MOLECULAR DOCUMENTATION OF T(15,17) CHROMOSOMAL TRANSLOCATION

Two morphologic variants of acute promyelocytic leukemia (AML M3) are recognized-the hypergranular form, in which Auer rods are usually nume rous; and the microgranular form. The case of AML M3 reported here lac ked numerous Auer rods but was hypergranular and demonstrated prominen t giant Chediak-Higashi-like granules in the leukemic cells. Although routine karyotypic studies were inconclusive, a t(15;17) translocation was documented using Southern blot genotypic analysis and probes for the retinoic acid receptor-alpha and pml genes. This is the first case of this unusual morphologic anomaly in which the granules are describ ed in routine histologic sections and the first with evidence of a t(1 5;17) chromosomal translocation. It also illustrates the importance of Southern blot analysis in suspected cases of AML M3 with ''negative'' karyotypic studies.