Nevus

Nevus

Definition: A nevus is a benign, pigmented lesion that can occur in the eye. On the skin, a nevus is often referred to as a mole.  The most common location for a nevus in the eye is on the iris, the colored part of the eye which surrounds the pupil.  Nevi can also be found in the choroid, which is the vessel-filled tissue that lies beneath the retina in the back of the eye.  Typically nevi are followed to detect changes that may indicate a transformation into a malignancy.  Nevi rarely transform into cancerous lesions (melanomas), but if any change is noticed in these lesions, treatment may be suggested.

Cause: Nevi are either congenital (present at birth), or form early in childhood from a benign overgrowth of pigment producing cells called melanocytes.  Melanocytes are present in multiple tissues of the body, including the skin and the eye.

Symptoms:  Typically, nevi in the eye are asymptomatic.  

Treatment: Usually no treatment is needed for nevi of the eye. Occasionally, a large nevus will be photographed and observed to make sure it is not growing or changing shape. Rarely, a large or atypical nevus, or a nevus that appears to have changed to a malignant melanoma, will be treated with surgery and/or radiation.

Prognosis: Nevi are almost always benign, and only rarely become cancerous.