Diagnosis of primary vitreoretinal lymphoma masquerading infectious retinitis by retinal biopsy.

purposeTo report a case of primary vitreoretinal lymphoma masquerading as infectious retinitis that was diagnosed via a retinal biopsy. OBSERVATIONS: A 72-year-old female patient was referred to our ophthalmology clinic for evaluation of retinitis and vasculitis in the right eye (OD). On examination, best-corrected visual acuities (BCVAs) were hand motions OD and 20/20 in the left eye (OS). Fundus examination revealed optic disc edema and diffuse retinal whitening superior to the superotemporal arcade OD. Given the high suspicion of infectious retinitis, the patient was treated with intravitreal foscarnet, systemic acyclovir, and oral prednisone and underwent a comprehensive uveitis workup, which was unremarkable for viral and autoimmune entities. Given the patient's history of diffuse large B cell lymphoma with cutaneous involvement, vitreoretinal lymphoma was suspected, prompting pars plana vitrectomy with a retinal biopsy. Biopsy and immunohistochemistry results were consistent with B-cell lymphoma, and the patient was treated with high-dose methotrexate and rituximab. At 5-month follow-up, BCVAs were hand motions OD and 20/30 OS, and fundus examination demonstrated disc edema with resolution of retinal whitening OD. She responded well to the treatment with regression of vitreoretinal lymphoma on examination and is being monitored closely for lymphoma recurrence. CONCLUSIONS AND IMPORTANCE: Although uncommon, patients with vitreoretinal lymphoma may masquerade as infectious retinitis, and vitreoretinal lymphoma should be suspected when refractory to antiviral therapy and in the setting of a negative workup for viral etiologies. Vitrectomy with retinal biopsy may be considered to aid the diagnosis of vitreoretinal lymphoma although careful consideration of the risks and benefits is warranted.