Intrathecal rituximab in pediatric CD20-positive central nervous system limited lymphoproliferative disease: report of two cases and literature review.

Isolated central nervous system (CNS) involvement due to posttransplantation proliferative disorder (PTLD) is even rarer, with only a few cases reported in the literature. CNS involvement in patients with mature B-cell non-Hodgkin's (NHL) and PTLD confers a significantly worse prognosis as compared to patients without CNS lymphoma disease. Treatment of CNS lymphoma (CNSL) is challenging due to resistance to conventional cytotoxic and intrathecal chemotherapy. Here, we report the successful use of intrathecal rituximab in two pediatric cases of CD20 + isolated CNSL that had failed to respond to standard chemotherapy, intravenous rituximab and Epstein-Barr virus (EBV)-specific cellular therapy. However, after repeated intrathecal administration of rituximab, both patients' clinical symptoms were alleviated, which has created opportunities for further treatments. We emphasise that intrathecal rituximab may be a safe and promising strategy for the treatment of pediatric patients with CD20 + isolated CNSL. The literature on this topic was also reviewed.