An unusual case of a pigment epithelial cyst masquerading as a uveal melanoma after zoster ophthalmicus-related iris atrophy

PURPOSE: To report the case of a 69-year-old male who was referred for a previously unidentified pigmented iris lesion with surrounding iris atrophy masquerading as an iris melanoma. OBSERVATIONS: A sharply demarcated pigmented lesion extending from the trabecular meshwork to the pupillary margin was identified in the left eye. There was adjacent iris stromal atrophy. Testing was consistent with a cyst-like lesion. The patient later described a prior episode of ipsilateral herpes zoster involving the ophthalmic division of cranial nerve five. CONCLUSIONS AND IMPORTANCE: Iris cysts present an uncommon iris tumor, often going unrecognized especially if located on the posterior iris surface. When they present acutely, as in this case where a previously unidentified cyst was revealed following zoster-induced sectoral iris atrophy, these pigmented lesions can be concerning for malignancy. Accurately identifying iris melanomas and differentiating them from benign iris lesions is imperative.