For recipients of allogeneic hematopoietic stem cell transplantation (HSCT), Mycobacterium tuberculosis may act as a signi¢cant opportunistic pathogen in the early posttransplantation period, especially in areas where tuberculosis (TB) is endemic. Incidence and risk factors for mycobacterial infection diagnosed in the post-HSCT period have been reviewed previously in large cohorts of patients (1^6), with factors such as matched unrelated and mismatched transplantations, treatment with total body irradiation, and graftversus- host disease (GVHD) having a signi¢cant impact onTB incidence. However, studies of TB diagnosed solely in the pediatric HSCT population are scarce, and little is known of prognostic factors after initiation of anti-TB medication. Most importantly, the severe immunosuppression that characterizes the post-HSCTperiod may have a.
