Iris melanomas rarely result in death. The reason for this difference in behavior is unclear but may be due to the fact that most iris melanomas are small when first detected. They also tend to have an innocuous histologic appearance that consists predominately of spindle cells with rather bland nuclei. Some observers have speculated that most iris melanomas are actually nevi. 4 Iris melanomas appear as well-circumscribed, pigmented masses ranging in color from beige to light tan to dark brown.
Bulky tumors can encroach or touch the cornea.
There are no absolute clinical criteria for distinguishing iris nevi from melanoma. Perhaps the two most important clinical features are documented growth and absolute size. These lesions are often vascular and may bleed spontaneously into the anterior chamber. The accuracy of clinical diagnosis of retinoblastoma is high. Most retinoblastomas have a characteristic clinical appearance.