Primary Vitreoretinal Lymphoma -- A Review.

Primary vitreoretinal lymphoma (PVRL) is the most common intraocular lymphoma occurring in the eye. It is a high-grade typically B-cell malignancy, arising in the retina, and is often associated with central nervous system (CNS) disease and thereby a poor prognosis. It needs to be distinguished from choroidal low-grade B-cell lymphomas, which do not disseminate to the brain and have a good prognosis. Because of the rarity of PVRL, information is lacking regarding its true incidence, its geographical or ethnic variation, and underlying risk factors apart from immunosuppression associated with human immunodeficiency virus (HIV) and Epstein Barr virus. PVRL often presents masquerading as other intraocular diseases and is therefore often associated with diagnostic delays. This is compounded by the fragility of the neoplastic B cells, which hampers vitrectomy yields and pathological work-up. The latter includes cytomorphology and immunoprofiling, with adjunctive tests such as cytokine analysis, polymerase chain reaction for clonality, MYD88 mutational testing, and possibly bespoke next generation sequencing. Recent examinations of PVRL and CNS lymphoma (CNSL) using whole genome sequencing confirm that these tumors arise from activated postgerminal center cells, reflecting their aggressive course in most cases. The treatment of PVRL varies between centers and is dependent on presence or absence of concomitant CNS disease. The prognosis remains poor, and yet progress is steadily being made through international collaborative clinical trials.