Primary intraventricular lymphoma with diffuse leptomeningeal spread at presentation.

Dear Editor, Primary central nervous system lymphoma (PCNSL) is a rare tumour accounting for 4% of all brain neoplasms.1 In immunocompetent patients, it tends to present as a large solitary hemispheric mass with periventricular lesions giving rise to ependymal seeding in 38% of the cases.2 Leptomeningeal metastases of the PCNSL at presentation are rare, accounting for only 2.3% of the cases.3 We present a rare case of primary intraventricular PCNSL with diffuse leptomeningeal spread at presentation. In this case study, we discuss the differential diagnoses and diagnostic approach to disseminated intraventricular masses.