Primary Central Nervous System Lymphoma Associated With Immune Deficiency and Dysregulation: Challenges in Treatment and Management.

Lymphomas associated with immune deficiency and dysregulation (IDD) rarely occur in the central nervous system (CNS). Discontinuing immunosuppressives is the first choice of treatment, but it is often not feasible after solid organ transplantation (SOT). We report a case of primary CNS lymphoma (PCNSL) arising in IDD with an unusual clinical course. A 47-year-old woman with a history of chronic use of immunosuppressives after a kidney transplantation presented with a one-month history of headaches and left-sided weakness for two days. Gadolinium (Gd)-enhanced MRI of the brain revealed a mass lesion with ring enhancement in the right basal ganglia, and diffusion-weighted imaging (DWI) confirmed cerebral infarction in the right corona radiata. All blood tumor markers were negative, but cerebrospinal fluid analysis showed a highly elevated β2-microgrobulin (MG). PET showed relatively high 18F-fluorodeoxyglucose (FDG) uptake within the area of ring enhancement on MRI, but no obvious accumulations in tissues outside the CNS. The history and results of laboratory examinations and imaging studies suggested an initial diagnosis of malignant lymphoma. Following resection, the lesion was diagnosed histologically as diffuse large B-cell lymphoma (DLBCL). The tumor was negative for Epstein-Barr virus (EBV)-encoded small RNA; however, blood tests confirmed the presence of EBV-DNA (2.81 LogIU/mL). As the immunosuppressive therapy could not be discontinued, rituximab was initiated on the day after surgery. However, the lesion progressed rather than regressed, and postoperative radiation treatment was administered. MRI four months after surgery showed tumor shrinkage. CNS lymphoma arising in IDD should be considered when a mass lesion develops during long-term immunosuppressive therapy after transplantation.