INVITRO AGAR CULTURE PATTERNS IN PRELEUKEMIA AND THEIR CLINICAL SIGNIFICANCE

Nineteen patients with preleukemia were studied by in vitro agar culture to determine if this method could predict their clinical outcome. As in oligoleukemia, five growth patterns were identified: (1) Category (Cat) I-A with low plating efficiency, normal cluster/colony ratio and normal cell differentiation in the colonies; (2) Cat I-B with high plating efficiency, normal cluster/colony ratio and normal cell differentiation in the colonies; (3) Cat II with low colony and high cluster incidence and normal cell differentiation in the colonies; (4) Cat III-A with growth of excessive number of clusters (3-20 cell size) only, containing predominantly blast cells; and (5) Cat III-B with excessive number of clusters (3-39 cell size) and a few blast cell colonies. Growth patterns II, III-A and III-B are characteristic of acute myeloid leukemia and therefore called leukemic growth patterns. Twelve of 19 patients had a Cat I-A (non-leukemic) growth pattern. Five patients were identified with a leukemic growth pattern (two in Cat II, two in Cat III-A and one in Cat III-B), and two patients with Cat I-B. Survival was significantly longer (P = <0.05) in Cat I-A than in the other categories. Progression to leukemia was more common ( 6 7) and faster (median 20 weeks, range 2-32 weeks) in Cat I-B, II, III-A and III-B as compared to Cat I-A (1 of 12 at 40 weeks). Of seven patients who progressed to leukemia, four presented with a leukemic culture pattern. Of the three patients with a non-leukemic culture pattern, two were followed sequentially. In one, change from I-A to III-A occurred 16 weeks in advance and in the other from I-B to III-A simultaneously with leukemic progression. Patients with preleukemic syndrome who, in in vitro culture, reveal leukemic growth patterns, may represent true preleukemia and progress rapidly to overt leukemia. © 1979.