SUBGROUPS OF OLIGOLEUKEMIA AS IDENTIFIED BY INVITRO AGAR CULTURE

Sixty-five patients with a diagnosis of oligoleukemia (myeloid leukemia with < 50% marrow leukemic infiltrate) were studied by in vitro agar culture to delineate various growth patterns and their prognostic significance. Five in vitro growth patterns were observed: (1) Category (Cat) I-A with low colony and cluster incidence, normal cluster/colony ratio and normal cellular differentiation in colonies; (2) Cat I-B with normal to high number of colonies and clusters, normal cluster/colony ratio and normal cellular differentiation in colonies; (3) Cat II with excessive clusters and a low number of colonies, high cluster/colony ratio and normal differentiation of cells in the colonies; (4) Cat III-A with excessive number of clusters only of ≤ 20 cells size; and (5) Cat III-B with excessive number of clusters of > 20 cell size with or without colonies consisting predominantly of blast cells. Culture patterns of Cat III-A and III-B resemble those observed in acute myeloid leukemia and therefore are called leukemic culture patterns. Patients in Cat I-A (non-leukemic culture pattern) survive longer (P = < 0.04) and progress less rapidly to acute leukemia (P = < 0.03) when compared with those in Cat III-A and III-B. Also the rate of increase in leukemic blast cell infiltrate is slower in Cat I-A than in Cat III-A and III-B. Patients with non-leukemic in vitro growth pattern are associated with a relatively benign clinical course and those in Cat III-A and III-B (leukemic growth pattern) are associated with a more aggressive leukemic disorder. © 1979.