Melanocytic Conjunctival Tumors

Melanocytic Conjunctival Tumors

Conjunctival Nevus

Birthmarks can occur on the conjunctiva as on the skin. They are usually located near the limbus in the temporal portion of the palpebral fissure, less frequently on the lacrimal caruncle. These benign, slightly raised epithelial or subepithelial tumors are congenital. Fifty percent of nevi contain hollow cys-tic spaces (pseudocysts) consisting of conjunctival epithelium and goblet cells. Conjunctival nevi may be pigmented (Fig. 4.24a) or unpigmented (Fig. 4.24b), and they may increase in size as the patient grows older. Increas-ing pigmentation of the nevus as a result of hormonal changes during preg-nancy or puberty or from exposure to sunlight can simulate an increase in the size of the nevus, as can proliferation of the pseudocysts. Conjunctival nevi candegenerate into conjunctival melanomas (50% of conjunctival melanomasdevelop from a nevus). Therefore, complete excision and histologic diagnostic studies are indicated if the nevus significantly increases in size or shows signs of inflammation.

Photographs should always be taken during follow-up examinations of conjunctival nevi. Small clear watery inclusion cysts are always a sign of a conjunctival nevus.

Conjunctival Melanosis

Definition

Conjunctival melanosis is a pigmented thickening of the conjunctival epi-thelium (Fig. 4.24c).

Epidemiology: Conjunctival melanosis is rare like all potentially malignantor malignant tumors of the conjunctiva.

Etiology: Unclear.

Symptoms: Acquired conjunctival melanosis usually occurs after the age of

Typical symptoms include irregular diffuse pigmentation and thickening of the epithelium that may “come and go.”

Diagnostic considerations: Acquired conjunctival melanosis is mobile withthe conjunctiva (an important characteristic that distinguishes it from con-genital melanosis). It requires close observation with follow-up examinations every six months as it can develop into a malignant melanoma

.Differential diagnosis: This disorder should be distinguished frombenigncongenital melanosis (see below), which remains stable throughout thepatient’s lifetime and appears more bluish gray than brownish. In contrast to acquired melanosis, it is not mobile with the conjunctiva.

Treatment: Because the disorder occurs diffusely over a broad area, treat-ment is often difficult. Usually it combines excision of the prominent deeply pigmented portions (for histologic confirmation of the diagnosis) with cryo-coagulation of the adjacent melanosis and in some cases with postoperative radiation therapy.

Clinical course and prognosis: About 50% of conjunctival melanomasdevelop from conjunctival melanosis (the other 50% develop from a conjunc-tival nevus; see above). Conjunctival melanomas are not usually as aggres-sively malignant as skin melanomas. The radical resection required to remove the tumor can be a problem. Multiple recurrences will produce significant conjunctival scarring that can result in symblepharon with fusion of the eye-lid skin and conjunctiva. Where the tumor has invaded the eyelids or the deeper portions of the orbit, orbital exenteration will be unavoidable to completely remove the tumor.

Congenital Ocular Melanosis

Benign congenital melanosis (Fig. 4.24d) is subepithelial in the episclera. Theconjunctival epithelium is not involved. Pigmentation is bluish gray. In con-trast to acquired melanosis, congenital melanosis remains stable and station-ary throughout the patient’s lifetime. In contrast to nevi and acquired mela-nosis, congenital melanosis remains stationary when the conjunctiva above it is moved with forceps. Congenital ocular melanosis can occur as an isolatedanomaly of the eye or in association with skin pigmentations (oculodermalmelanosis or Ota’s nevus). Although the tumor is benign, evidence suggests that malignant melanomas in the choroid occur more frequently in patients with congenital melanosis.