Cytomegalovirus Retinitis Mimicking Acute Retinal Necrosis During Upadacitinib Therapy.

Cytomegalovirus (CMV) retinitis classically occurs in patients with advanced human immunodeficiency virus infection but may also affect non-HIV patients with impaired cellular immunity and can resemble acute retinal necrosis (ARN). A 74-year-old woman receiving upadacitinib 15 mg/day for rheumatoid arthritis presented with decreased vision and a central dark scotoma in the left eye. Widefield montage imaging obtained with the Mirante SLO/OCT platform (NIDEK Co., Ltd., Gamagori, Aichi, Japan) showed temporal to inferotemporal retinal whitening with hemorrhages, vitreous haze, marked perivascular changes, and occlusive vasculitis. Intravenous acyclovir was started for presumed ARN. Aqueous humor polymerase chain reaction subsequently detected CMV DNA at 6.85 × 10⁴ copies/mL, whereas herpes simplex virus and varicella-zoster virus results were negative; HIV RNA was undetectable and peripheral-blood CMV antigenemia was negative. Treatment was changed to oral valganciclovir, and upadacitinib was discontinued. The valganciclovir dose was reduced after renal dysfunction developed. The retinal whitening regressed into atrophic scars without retinal detachment or fellow-eye involvement, but vision remained poor because of macular ischemia and outer retinal damage. This case illustrates that CMV retinitis in a non-HIV immunosuppressed patient may present with an ARN-like phenotype and severe occlusive vasculitis. Early ocular fluid testing can identify the pathogen and redirect antiviral treatment; the temporal association with upadacitinib should not be interpreted as proof of drug-specific causality.