The Power of Hematopoietic Stem Cell Transplantation (HSCT): A Curative Approach for Diffuse Large B-Cell Lymphoma (DLBCL) Incidentally Detected in a SCID Baby.

Lymphoma is a rare complication of X-linked severe combined immunodeficiency (X-SCID) caused by IL2RG deficiency. We report an infant with IL2RG-SCID who developed diffuse large B-cell lymphoma (DLBCL) during pretransplant evaluation. A male infant with T-B+ SCID was diagnosed at 1 month of age and referred for hematopoietic stem cell transplantation (HSCT). Pretransplant imaging unexpectedly revealed a thoracic mass, and biopsy confirmed EBV-negative DLBCL. Rituximab and low-dose chemotherapy failed to reduce the mass and were complicated by severe infections. The patient subsequently underwent unconditioned haploidentical HSCT with posttransplant cyclophosphamide. Full donor T-cell chimerism was achieved by Month 3, and complete resolution of the lymphoma was observed 15 months after HSCT. Successful HSCT and immune reconstitution may achieve lymphoma control in IL2RG-SCID when conventional chemotherapy is poorly tolerated. Trial Registration: The authors have confirmed clinical trial registration is not needed for this submission.