Pretreatment bone marrow cytogenetic studies were included for 1664 patients with acute lymphoblastic leukemia (ALL) accrued to Pediatric Oncology Group (POG) 8035 laboratory classification study from May 1981 through January 1986. There was a significant difference (P = 0.0001) in distribution of stem-line karyotype (normal, hypodiploid, pseudodiploid, or hyperdiploid) among children with early pre-B, pre-B, or T-cell ALL, with early pre-B patients demonstrating a higher proportion of hyperdiploid karyotypes with modal chromosome numbers greater than 51. Cytogenetic classification of 1216 patients with early pre-B or pre-B ALL evaluable for duration of event-free survival (EFS), with median follow-up of 42 months, showed a significant prolongation of five-year EFS associated with hyperdiploidy greater than 51 (75%; standard error [SE] = 5%) compared with hyperdiploidy 47 to 51 (46%; SE = 7%), hypodiploidy (55%; SE = 11%), and pseudodiploidy (45%; SE = 7%) (P = 0.0001). Five-year EFS was intermediate for patients with normal (58%), constitutionally abnormal (66%), or unsuccessful analyses (66%). The breakpoint defining hyperdiploidy associated with better prognosis was best defined as greater than 51 (P = 0.0002). Of 239 children with hyperdiploid karyotypes, analysis of the contribution of each chromosome to EFS duration showed a significant association between improved EFS and additional chromosome(s) six (P = 0.02). Chromosome translocation was associated with shorter EFS (P = 0.0001).

As part of a comprehensive prospective clinicopathologic study by the Pediatric Oncology Group (POG), 2,092 children with acute lymphoblastic leukemia (ALL) were evaluated by uniform morphologic, cytochemical, and immunologic methods to assess the frequency and implications of granular lymphoblasts. All cases were Sudan black or myeloperoxidase negative and met French-American-British (FAB) morphologic criteria for ALL. Granular ALL, characterized by the presence of more than 5% marrow blasts with at least three clearly defined azurophilic cytoplasmic granules, was identified in 56 of the 1,252 fully studied cases (4.5%). The frequency of granular features did not differ among early pre-B (4.3%), pre-B (3.6%), and T (5.8%) ALL; no cases were identified among the 12 patients with B ALL. Within the early pre-B/pre-B group, granular ALL was equally distributed between good- and poor-risk clinical groups but was more frequent among FAB L2 than FAB L1 cases (12% vs. 2%; P less than or equal to 0.001). Patients were treated with standard POG protocols for early pre-B/pre-B and T ALL. Complete remission (CR) rates were significantly lower for those with granular lymphoblasts, regardless of risk group, immunophenotype, or FAB type. Analysis of event-free survival (EFS) showed a significantly poorer outcome for granular early pre-B/pre-B cases with FAB L2 morphologic characteristics (P less than 0.001) and for those classified as poor risk (P = 0.015). These findings suggest a relationship between granules and L2 morphologic characteristics in childhood ALL and indicate that the presence of granular lymphoblasts conveys a worse prognosis for certain subgroups of children with ALL.