Role of vitreous cytology in the diagnosis of primary central nervous system lymphoma: A report of an unusual presentation.

Primary central nervous system lymphoma (PCNSL) is a rare subtype of non-Hodgkin lymphoma confined to the brain, spinal cord, meninges, intraocular compartment, and cranial nerves. Intraocular lymphoma (IOL) is a rare subtype of PCNSL. Intravitreal involvement by a PCNSL is an infrequent but potentially fatal event. The role of vitreous cytology in diagnosing IOLs is vital but has been sporadically described in the literature due to its variable sensitivity. Herein, we present a case of PCNSL, who primarily presented with ocular symptoms and could be accurately diagnosed based on vitreous cytology and subsequently confirmed on stereotactic brain biopsy.