Iris melanoma in ocular melanocytosis.

A pigmented, circumscribed iris lesion thought to be a nevus was noted in the right eye of a 64-year-old man with congenital ocular melanocytosis. Although the patient had excess episcleral and choroidal pigmentation, the iris in the affected eye was blue. Two years later, growth was documented, suggesting that the lesion was malignant. The tumor was resected by a sector iridectomy and studied by light microscopy. Histopathologically, the tumor was shown to be a malignant melanoma of the mixed-cell type. No evidence of congenital melanocytosis was found in the adjoining normal iris. This is a well-documented case of a malignant melanoma of the iris arising in a blue, uninvolved iris in a patient with sectoral congenital ocular melanocytosis. Although this specific association has not been previously reported, we believe that any pigmented uveal tumor occurring in the setting of congenital ocular melanocytosis should be observed closely for growth that can signal malignant transformation.