Conjunctival Nevus

Conjunctival nevus is the commonest melanocytic lesion of the conjunctiva, a benign proliferation of melanocytic nests.

• Appears in childhood or adolescence, with increasing pigmentation at puberty. Usually single, unilateral.
• Locations: limbal, interpalpebral bulbar conjunctiva (temporal or nasal), caruncle, plica semilunaris. Rare on tarsal conjunctiva or fornix (should prompt suspicion).
• Types by histology: junctional, compound, subepithelial. Compound is most common.
• Malignant transformation is rare (less than 1 percent), but about 25 percent of conjunctival melanomas arise from nevi.

• Well circumscribed, flat or slightly elevated, brown to pale lesion, often with cystic spaces (seen in about 65 percent).
• Variation in pigment, with amelanotic nevi appearing as pink, and darkening during puberty or pregnancy.
• Painless, slowly growing, with no feeder vessels and no corneal extension.
• Features of concern for melanoma: new onset in adults, rapid growth, increased pigmentation, prominent feeder vessels, loss of cysts, nodularity, extension over the cornea, fixation to sclera, or lesions in the fornix, tarsus or palpebral conjunctiva.
• Primary acquired melanosis (flat, patchy, diffuse brown pigment in adults, unilateral) is a distinct entity that carries melanoma risk.

• Slit lamp examination with measurement of size and photography for serial comparison (every 6 to 12 months).
• Anterior segment optical coherence tomography (thickness and cysts) and ultrabiomicroscopy where needed.
• Examine fornices, tarsus, and fundus; palpate lymph nodes if a malignant lesion is suspected.
• Excisional biopsy (no touch technique) for suspicious or enlarging lesions, for histology.
• Differential: primary acquired melanosis, racial melanosis (bilateral, perilimbal in dark skinned individuals), melanocytoma, ocular melanocytosis, squamous neoplasia, pigmented pterygium, foreign body.

• Most nevi are observed with photographic documentation every 6 to 12 months.
• Indications for excision: growth, change in colour, irritation, cosmetic concern, or suspicion of melanoma.
• Surgical technique: no touch excision with 1 to 2 mm clear margins, avoiding the tumour being contacted, with cryotherapy to the conjunctival margins and conjunctival reconstruction with amniotic membrane or primary closure. Send for histology.
• Patient education: report change in size or colour; protect from ultraviolet light.
• Follow up after excision at 3 to 6 months for recurrence.