PLEURAL RELAPSE DURING HEMATOPOIETIC REMISSION IN CHILDHOOD ACUTE LYMPHOBLASTIC-LEUKEMIA

Purpose: This report describes an isolated pleural relapse during hema topoietic remission in a child previously treated for acute lymphoblas tic leukemia (ALL). Patient and Methods: An 11-year-old boy had a coug h and exertional dyspnea 34 months after an initial diagnosis of ALL a nd 10 months after completion of therapy. Imaging studies revealed a l arge left pleural effusion. Bone marrow and cerebrospinal fluid studie s were negative for disease at this time. Results: Histopathologic exa mination of biopsy samples revealed cells with morphologic features of acute lymphoblastic leukemia blasts. Immunophenotyping, cytogenetic, and gene rearrangement studies confirmed the presence of a leukemic bl ast cell population similar to that detected at initial diagnosis. An isolated extramedullary relapse in the pleura was diagnosed. The patie nt underwent successful reinduction therapy and subsequently a matched unrelated donor bone marrow transplant; he died of disseminated infec tion in the posttransplant period. Conclusions: Unusual extramedullary sites of relapse are recognized with increasing frequency as long-ter m survival in childhood ALL improves. The length of the disease-free i nterval before relapse is felt to be of prognostic significance. Isola ted relapse to the pleural space has not previously been described. Th e mechanism for persistence of leukemic clones in patients who appear to be in hematopoietic remission is unknown.