Primary Central Nervous System Lymphoma With Testicular and Prostatic Involvement: A Case Report

Diffuse large B-cell lymphoma (DLBCL) is an aggressive subtype of non-Hodgkin lymphoma that most commonly presents with nodal disease, while primary involvement of the central nervous system (CNS) is rare, particularly in immunocompetent patients. We describe the case of a 41-year-old immunocompetent male who presented with progressive left-sided hemiparesis, ipsilateral facial palsy, severe headache, and decreased level of consciousness. Neuroimaging findings and histopathological examination confirmed the diagnosis of primary CNS DLBCL. Subsequent systemic evaluation with PET-CT revealed increased metabolic activity in the testicular and prostatic regions, consistent with secondary extranodal involvement. The patient was treated with a MATRIX-based chemotherapy regimen, including high-dose methotrexate, cytarabine, and rituximab, in accordance with current guidelines for primary CNS lymphoma. This case highlights an unusual presentation of primary CNS DLBCL with early systemic dissemination to testicular and prostatic tissue, underscoring the importance of comprehensive staging and prompt initiation of high-dose methotrexate-based therapy to optimize clinical outcomes.