Metastatic squamous cell carcinoma masquerading as acute retinal necrosis

Purpose: To describe a case of retinal and optic nerve metastases masquerading as acute retinal necrosis secondary to primary squamous cell carcinoma of the lung. Observations: A 66-year-old male with a history of Stage IV lung cancer, actively on chemotherapy, presented with right eye vision loss, an afferent pupillary defect, and partial visual field deficiencies. Exam revealed vitritis, macula-involving infiltrative retinitis, optic neuritis, and vasculitis of the right eye. The patient was treated empirically for acute viral retinitis with intravitreal foscarnet and ganciclovir injections and oral acyclovir and trimethoprim-sulfamethoxazole. A diagnostic pars plana vitrectomy with vitreous biopsy, intravitreal antivirals and silicone oil fill was performed. The resulting cytology was positive for malignant squamous cell carcinoma. Conclusions and importance: We present a unique case of primary squamous cell carcinoma metastasizing to the retina and optic nerve which masqueraded as an acute viral retinitis. To date, there have not been any reported cases on Pubmed or Google Scholar at publication time of known squamous cell carcinoma metastases to the retina that demonstrated interval growth leading to emergent elevations in intraocular pressure (IOP). This case demonstrates the importance of considering metastasis when encountering an atypical acute retinal necrosis case, as well as bring awareness to the possibility that elevated IOP may be the first sign of interval metastases, despite surgical debulking, in cases involving known tumor metastases to the retina.