Diagnosis of acute leukemia. Variability of morphologic criteria.

The diagnosis of acute leukemia depends on the morphologic appearance of Romanowsky-stained blast cells. Three commonly used and accepted criteria for distinguishing among blast cells of different acute leukemias are (1) nuclear chromatin pattern, (2) appearance of nucleoli, and (3) nuclear-cytoplasmic ratio. It is sometimes assumed that Romanowsky stains do not differ in their abilities to demonstrate characteristic features of blast cells. In the present study six different Romanowsky stains were applied to smears from a single bone marrow aspirate from each of 22 patients with acute leukemia. Marked, stain-dependent variation in the appearances of the same blast cell population was repeatedly observed for all modalities except nuclear-cytoplasmic ratio. The authors caution against generalizations regarding morphology and suggest that the exact stain employed is a significant variable in morphologic studies.