Localized bone marrow relapse in acute lymphoblastic leukemia

Localized bone marrow relapse is rare in acute lymphoblastic leukemia. Discordant bone marrow specimens were found in an 11-year-old asymptomatic girl who had been in remission for six years and off chemotherapy for 2 1/2 years. One bone marrow sample showed marked leukemic infiltration, whereas marrow from another site was normal. Three months later, with normal peripheral blood counts, she developed severe back pain and x-ray evidence of vertebral collapse and periosteal changes in the pubic bone. At that time three of the four areas of bone marrow sampled showed leukemic involvement. Reinduction therapy was begun, and she is now in remission on maintenance chemotherapy. At this time, it is unclear whether routine performance of marrow aspirations and biopsies from multiple sites, in periodic follow-up examinations of patients with acute leukemia would allow earlier detection of relapse frequently enough to justify the procedure. The issue of localized bone marrow involvement, if more common than previously reported, should be addressed at the time a decision is being made to discontinue therapy.