RESUMEN
RATIONALE: Primary central nervous system lymphoma (PCNSL) is a rare, highly malignant form of non-Hodgkin lymphoma categorized under the diffuse large B-cell type. It accounts for merely 1% of all non-Hodgkin lymphoma cases and comprises approximately 3% of all brain tumors. The involvement of the cerebellum is observed in only 9% of these cases. Recently, we came across an unusual instance: a young man presenting with multiple lesions located specifically within the cerebellum. PATIENT CONCERNS: A 26-year-old male was admitted to the hospital due to severe headaches. He has a medical history of sporadic headaches, accompanied by dizziness, nausea, and vomiting persisting for a month. Over the last 10 days, his headaches have intensified, coupled with decreased vision and protrusion of the eyeballs. Magnetic resonance imaging (MRI) revealed abnormal signals in both cerebellar hemispheres. DIAGNOSES, INTERVENTIONS, AND OUTCOMES: Diagnostic procedures included cerebellar biopsy, posterior fossa decompression, and lateral ventricle drainage. Histopathological examination identified diffuse large B-cell lymphoma (DLBCL) with high proliferative activity. To minimize neurotoxicity, chemotherapy involved intrathecal methotrexate (MTX) injections combined with the CHOP program. The patient has shown good tolerance to the treatment so far. LESSONS: While the definitive optimal treatment approach remains elusive, current chemotherapy centered on high-dose MTX stands as the standard induction therapy. Integrating surgery with radiotherapy and chemotherapy significantly extends patient survival.