Diffuse Peripapillary Choroidal Melanoma That Evolved from a Small Presumed Choroidal Nevus Successfully Treated with Gamma Knife Radiotherapy

PURPOSE To report a case of diffuse peripapillary choroidal melanoma which began as a small choroidal nevus and was successfully treated with gamma knife radiotherapy. METHODS Observational case report. RESULTS A 31-year-old visually asymptomatic man presented for a routine eye examination and was noted to have a small choroidal nevus. Six years later, the lesion had become a diffuse juxtapapillary choroidal melanoma with a thickness of 1.9 mm. Given the peripapillary location of the tumor with involvement of about 6 clock hours of the disk, Leksell Gamma Knife radiotherapy was performed. At 5.5 years after radiation therapy, visual acuity remained 20/20. The lesion thickness had decreased to 1.5 mm, and there was no interval growth of any margins. CONCLUSION Small choroidal nevi carry low malignant potential but still deserve photographic documentation when possible with regular follow intervals. Gamma knife radiotherapy can be considered for tumors abutting the optic nerve, especially when plaque radiotherapy may be technically difficult.