Initial prognostic factors and lymphoblast-erythrocyte rosette formation in 109 children with acute lymphoblastic leukemia.

Bone marrow lymphoblasts from 109 children admitted with untreated acute lymphoblastic leukemia (ALL) were tested for spontaneous rosette formation with sheep erythrocytes. Twenty-six children (24%) had lymphoblasts that formed rosettes (E+). Of 13 initial clinical characteristics, 8 were significantly associated with E+ lymphoblasts: mediastinal enlargement (86% of patients E+), leukocyte counts over 100 X 10(9)/liter (65% E+), nodes greater than 2 cm in any diameter (65% E+), age over 5 yr (46% E+), hemoglobin over 8 g/dl (44% E+), hepatomegaly greater than 5 cm (38% E+), boys (35% E+), and lymph node enlargement outside of the cervical area (28% E+). Spleen size, initial platelet counts, and periodic acid-Schiff scores did not distinguish E+ from E- patients. Since few patients were black and few presented with central nervous system leukemia, the association of these two characteristics with E+ blasts could not be determined. A hierarchical classification scheme and a linear logistic regression model were used to define the patterns of characteristics associated with E+ lymphoblasts. The initial clinical characteristics and the poorer course of E+ patients suggest that ALL comprises at least two biologically and clinically distinct types. The E+ ALL may result from a leukemic transformation of a non-Hodgkin lymphoma.