Pigmented tumours of conjunctiva

1. Naevi or congenital moles. These are common pigmented lesions, usually presenting as grey gelatinous, brown or black, flat or slightly raised nodules on the bulbar conjunctiva, mostly near the limbus (Fig.1). They usually appear during early childhood and may increase in size at puberty or during pregnancy. Histologically, they resemble their cutaneous brethren. Malignant change is very rare and when occurs is indicated by sudden increase in
size or increase in pigmentation or appearance of signs of inflammation. Therefore, excision is usually indicated for cosmetic reasons and rarely for medical reasons. Whatever may be the indication, excision should be complete.

Fig. 1 conjunctival naevus

2. Precancerous melanosis. Precancerous melanosis (intraepithelial melanoma) of conjunctiva occurs in adults as 'superficial spreading melanoma'. It never arises from a congenital naevus. Clinically a small pigmented tumour develops at any site on the bulbar or palpebral conjunctiva, which spreads as a diffuse, flat, asymptomatic pigmented patch. As long as it maintains its superficial spread, it does not metastasize. However, ultimately in about 20 percent cases it involves the subepithelial tissues and proceeds to frank malignant change.
Treatment. In early stages local excision with postoperative radiotherapy may be sufficient. But in case of recurrence, it should be treated as malignant
melanoma.

3. Malignant melanoma (primary melanoma).

Malignant melanoma of the conjunctiva mostly arises de-novo, usually near the limbus, or rarely it may occur due to malignant change in pre-existing naevus. The condition usually occurs in elderly patients. Clinically it may present as pigmented or nonpigmented mass near limbus or on any other part of
the conjunctiva. It spreads over the surface of the globe and rarely penetrates it. Distant metastasis occurs elsewhere in the body, commonly in liver.
Histologically, the neoplasm may be alveolar, roundcelled or spindle-celled.
Treatment. Once suspected, enucleation or
exenteration is the treatment of choice, depending
upon the extent of growth.