Comparison of the cellularity and presence of residual leukemia in bone marrow aspirate and biopsy specimens in pediatric patients with acute lymphoblastic leukemia (ALL) at day 7–14 of chemotherapy

Abstract

Many pediatric chemotherapy protocols for treatment of ALL require a bone marrow examination at day 7 or day 14 after initiation of therapy. The usefulness of a bone marrow biopsy, in addition to an aspirate, has been a frequently asked question. This study addresses the evaluation of bone marrow cellularity and presence of residual leukemia in both aspirate and biopsy specimens in 45 consecutive pediatric patients (ages 1-19 years, 19 females, and 26 males) with ALL 7-14 days after initiation of therapy. 20/45 patients showed evidence of residual leukemia by bone marrow biopsy; 16/20 (80%) of these had evidence of residual leukemia in the aspirate specimen. Of the 4 aspirate specimens that did not demonstrate residual leukemia, 2 had <5% blasts and 2 had too few cells in the aspirate for evaluation. Of the 25/45 bone marrow biopsy specimens with no detectable residual leukemia, 14 of the aspirates had <5% blasts, and 11 had too few cells in the aspirate for evaluation. 13/45 (29%) of the aspirates had too few cells for a differential count. The bone marrow cellularity judged from the aspirate specimen was considered to be low (0-1+) in 34/45 patients. Of these 34 patients, the bone marrow biopsy showed hypocellularity (<20% cellularity) in 12/34, moderate cellularity (20-79% cellularity) in 14/34, and hypercellularity (>79% cellularity) in 8/34. We conclude that both the bone marrow aspirate and biopsy specimens provide important information in evaluating the response to chemotherapy in pediatric patients with ALL at day 7-14 of induction chemotherapy. The aspirate alone may be misleading in terms of cellularity in many patients and may not provide evidence of residual leukemia.