Case Report: Durable remission of intraocular mantle cell lymphoma after CD19 CAR-T therapy.

Mantle cell lymphoma (MCL) is an aggressive B-cell neoplasm with poor prognosis in refractory relapse. Intraocular (vitreoretinal) involvement is extremely rare and represents a diagnostic and therapeutic challenge due to the immune-privileged status of the eye and the risk of central nervous system (CNS) dissemination. Ocular relapse in mantle cell lymphoma has rarely been described, and evidence on the use of CAR-T therapy in this setting is lacking. We report the case of a 61-year-old man with stage IV-B MCL diagnosed in 2018, who experienced multiple relapses and developed intraocular infiltration confirmed by flow cytometric immunophenotyping of vitreous fluid in 2024. After bridging therapy with intravitreal methotrexate, the patient received CD19-directed CAR-T therapy with brexucabtagene autoleucel (Brexucel) as fifth-line treatment, achieving sustained complete metabolic remission with no ocular or systemic relapse after 19 months of follow-up. This case highlights the diagnostic value of flow cytometry in intraocular lymphomas and supports the expanding role of CAR-T therapy in refractory MCL with atypical sanctuary site involvement.