A Case of EBV-Driven Histiocytic Sarcoma as PTLD in a Pediatric Heart Transplant Patient.

Post-transplant lymphoproliferative disorders (PTLD) are typically EBV-driven neoplasms that occur after transplantation. Histiocytic sarcomas (HS) are rare malignancies. PTLD HS cases are even rarer. We discuss a case of multiorgan EBV+ HS PTLD in a pediatric male with a history of orthotopic heart transplant. He was initially treated broadly, then narrowed to disease-targeted therapy. Surveillance imaging showed improvement of his diffuse body lesions, but new leptomeningeal enhancements were identified. He developed neurological deterioration and succumbed to his disease. This is a rare case of PTLD manifesting as an EBV-driven HS with meningeal metastasis unresponsive to targeted therapy despite multiorgan improvement elsewhere.