Distinctive AgNOR patterns of myeloid and lymphoid blasts in acute leukemia

Bone-marrow aspiration smears of 38 cases of acute leukemia (19 acute lymphoblastic leukemia, 19 acute nonlymphocytic leukemia) were stained for argyrophilic nucleolar organiser regions (AgNOR). AgNOR were assessed numerically and morphologically. There were highly significant differences in AgNOR morphology between acute lymphoblastic leukemia and acute nonlymphocytic leukemia ANLL: lymphoblast AgNORs were usually small (<3 microm) "dots/chips," whereas myeloblasts showed larger "blebs," or a combination of the two types (complex structures). AgNOR number was significantly less in acute lymphoblastic leukemia. In acute nonlymphocytic leukemia cases, AgNOR number also showed direct correlation with Ki67 reactivity of leukemic blasts.