Unilateral acute iris transillumination syndrome with glaucoma and iris pigment epithelium dispersion simulating iris melanoma

PURPOSE: To report a patient with a unilateral presentation of glaucoma, pain, and acute iris transillumination syndrome simulating iris melanoma. OBSERVATIONS: A 53-year-old male presented with blurred vision and pain in his right eye several weeks following a respiratory sinus infection managed by oral azithromycin. Examination of the right eye was notable for elevated intraocular pressure of 46 mm Hg, an irregular mid-dilated pupil, and diffuse iris transillumination with pigmentary seeding on the iris surface, in the anterior chamber angle, and on the sclera, suspicious for diffuse iris melanoma with glaucoma and extrascleral extension. Ultrasound biomicroscopy (UBM) of the right eye revealed circumferential anterior chamber angle and trabecular meshwork involvement by an infiltrative process corresponding to the pigmented cells noted clinically, while the ciliary body was unremarkable. Following enucleation, histopathology showed extensive necrosis of the iris pigment epithelium, sphincter, and dilator muscles with melanophagic infiltration in the anterior chamber angle and episclera, mild chronic non-granulomatous iridocyclitis, and no evidence of a melanocytic neoplasm. Although immunohistochemical studies for herpes simplex virus (HSV) types 1 and 2, varicella-zoster virus, and cytomegalovirus were negative, qualitative real-time polymerase chain reaction on paraffin-embedded tissue detected HSV-1 DNA. The combined clinical, pathologic, and molecular findings were compatible with unilateral acute iris transillumination syndrome, likely HSV-1 associated. CONCLUSION AND IMPORTANCE: Unilateral acute iris transillumination syndrome with diffuse iris pigment epithelial loss can simulate iris melanoma. Prompt herpes viral studies may be informative.