Primary sarcoma of the iris is a relatively rare condition which occurs most frequently between the thirty-fifth and the fifty-fifth year. It is more common in females than in males. Pigmented spots in the iris, which are congenital, are not uncommon. They are seen as nevi, which usually lie in the anterior limiting layer and are often near the papillary border. These vary in size from a pinpoint to a large segment of the iris. Sometimes they are highly vascularized (nevus vasculosus). A nevus may give rise to a definite tumor, which is usually benign but may become malignant. Among 26 cases of innocent nevi under observation by Coats,1 the condition in 7 became malignant.
Serous cysts also occur in the iris. They are filled with a clear substance and develop within the stroma of the iris, so that their walls are formed by rarefied iris tissue. One also