Are most iris "melanomas' really nevi? A clinicopathologic study of 189 lesions.

A retrospective clinicopathologic study of 189 iris and iris and ciliary body lesions originally diagnosed as melanomas led to a nine-part histopathologic classification. Eighty-seven percent of lesions were reassigned to six benign categories and 13% were assigned to three malignant ones (spindle-B and epithelioid cell melanomas). There were no tumor deaths. The benign lesions were so classified if the constituent cells displayed bland cytologic characteristics, even though they might have produced a surface plaque or growth onto the trabecular meshwork and peripheral cornea. No clinical features were found to distinguish the benign from malignant tumors, including diffuse spread and the presence of glaucoma. The six recurrent tumors were equally divided between benign and malignant lesions. Thirty-six of 42 patients with incompletely excised lesions did not show further clinical problems on follow-up, establishing the inherently benign nature of most of the tumors.