Intracranial involvement of posttransplant lymphoproliferative disorder multiple myeloma.

We report a 61-year-old man with intracranial multiple myeloma (MM) presenting as a posttransplant lymphoproliferative disorder (PTLD) following a kidney transplant. Two months after his transplant, the man developed acute rejection with Epstein-Barr virus (EBV) viremia, requiring aggressive immunosuppression. Twenty months following transplantation, the patient presented with multiple neurologic deficits. Imaging revealed numerous lytic lesions in the skull, most conspicuously a 4.1cm right frontal skull mass with prominent intracranial extension. Histologic sections of the frontal bone lesion showed sheets of atypical plasma cells that were positive for CD138 and kappa immunoglobulin light chains. Chromogenic in situ hybridization for EBV-encoded small RNA was also positive. Plasma cell neoplasms, either as MM or a plasmacytoma, are one of the least common forms of PTLD, and their rarity limits the possibility of major studies to detail their behavior. Most often seen after renal transplantation, the majority are EBV-driven, similarly to other PTLD. While studies have demonstrated several risk factors, behavior and optimal management of PTLD plasma cell neoplasms are unknown. Plasma cell neoplasms affect the nervous system in a variety of ways but rarely via intracranial disease. MM usually presents initially with several classic signs and symptoms, but our patient's presentation was typical of a localized brain tumor with generalized and focal gross neurologic defects.