In acute myeloid leukemia, Auer rods are numerous in:September 2009

Ans. B: M3The diagnosis of AML is based on the presence of at least 20% myeloid blasts in the bone marrow. Myeloblast have delicate nuclear chromatin, two to four nucleoli, and more voluminous cytoplasm than lymphoblasts.The cytoplasm often contains fine, peroxidase-positive azurophilic granules.Auer rods, distinctive needle like azurophilic granules, are present in many cases; they are paicularly numerous in AML with the t(15;17) (acute promyelocytic leukaemia-M3).