Primary Leptomeningeal Lymphoma Presenting As Rapidly Progressive Hydrocephalus: Diagnosis and Symptom Relief Through Endoscopic Ependymal Biopsy and Third Ventriculostomy.

Primary leptomeningeal lymphoma (PLML) is a rare variant of primary central nervous system lymphoma, distinguished by the absence of parenchymal lesions. We describe an exceptionally rare case of PLML in an 86-year-old woman presenting with hydrocephalus. Magnetic resonance imaging showed ventricular enlargement over a two-week period, accompanied by faint periventricular contrast enhancement. To diagnose and treat her symptoms, an endoscopic ependymal biopsy and third ventriculostomy were performed concurrently, resulting in a pathological diagnosis of diffuse large B-cell lymphoma, specifically PLML, and symptom alleviation. The endoscopic approach proved effective and reasonable for the diagnosis and resolution of this atypical hydrocephalus.