Figure 8-6 Sebaceous gland carcinoma: various presentations. A, Presents as a unilateral blepharoconjunctivitis with injection, pannus, thickened eyelid margin, and eyelash loss. B, White nodules composed of neoplastic sebaceous cells may be present near the limbus. C, Neoplastic symblepharon is present nasally. D, Upper palpebral conjunctival thickening.

Papillary fronding may be present. (Reproduced with permission from Krachmer JH, Mannis MJ, Holland EJ, eds. Cornea. 3rd ed. Vol 1. Philadelphia: Elsevier/Mosby; 2011:472.)

Tumors of Neuroectodermal Origin

Table 8-2 lists the ocular surface tumors that arise from melanocytes, nevus cells, and other neuroectodermal cells. Some pigmented lesions of the globe are normal. For example, a pigment spot of the sclera is a collection of melanocytes associated with an intrascleral nerve loop or perforating anterior ciliary vessel. The term melanosis refers to excessive pigmentation without an elevated mass that may be congenital (whether epithelial or subepithelial) or acquired (whether primary or secondary). Conjunctival pigmentation can also occur from chronic exposure to epinephrine, silver, or mascara.

McLean IW, Cameron JD. Melanocytic neoplasms of the conjunctiva. In: Krachmer JH, Mannis MJ, Holland EJ, eds. Cornea. 3rd ed. Vol 1. Philadelphia: Elsevier/Mosby; 2011:477–484.

Shields CL, Demirci H, Karatza E, Shields JA. Clinical survey of 1643 melanocytic and nonmelanocytic conjunctival tumors. Ophthalmology. 2004;111(9):1747–1754.

Table 8-2

Benign Pigmented Lesions

Congenital epithelial melanosis

A conjunctival freckle, or ephelis, is a flat brown patch, usually of the bulbar conjunctiva near the limbus. It is more common in darkly pigmented individuals and is present at an early age.

Benign melanosis

Increasing pigmentation of the conjunctiva of both eyes is a common occurrence in middle-aged individuals with dark skin. This lightto dark-brown flat pigmentation is often most apparent at the limbus and becomes less prominent as one approaches the fornix (Fig 8-7). The stimulus for melanocytic hyperplasia is unknown but may be related to sunlight exposure. Streaks and whorls called striate melanokeratosis sometimes extend into the peripheral corneal epithelium.

Figure 8-7 Benign acquired melanosis in a patient with corneal arcus. (Courtesy of James Chodosh, MD.)

Ocular melanocytosis

Congenital melanosis of the episclera occurs in about 1 in every 2500 individuals and is more common in the black, Hispanic, and Asian populations.

PATHOGENESIS Ocular melanocytosis consists of focal proliferation of subepithelial melanocytes (blue nevi).

CLINICAL FINDINGS Patches of episcleral pigmentation appear slate gray through the normal conjunctiva (Fig 8-8) and are immobile and usually unilateral. Affected patients may have a diffuse nevus of the uvea evident as increased pigmentation of the iris and choroid. About one-half of patients with ocular melanocytosis have ipsilateral dermal melanocytosis (nevus of Ota) and a proliferation of dermal melanocytes in the periocular skin of the first and second dermatomes of cranial nerve V. The combined ocular and cutaneous pigmentations are referred to as oculodermal melanocytosis. Approximately 5% of cases are bilateral. Table 8-3 compares the various pigmented lesions of the conjunctiva.

Figure 8-8 Episcleral pigmentation in a patient with congenital ocular melanocytosis. (Courtesy of Kathryn Colby, MD, PhD.)

Table 8-3

MANAGEMENT Secondary glaucoma occurs in the affected eye in 10% of patients with ocular melanocytosis. Malignant transformation is possible but rare and seems to occur only in patients with fair complexions. Malignant melanoma can develop in the skin, conjunctiva, uvea, or orbit. The lifetime risk of uveal melanoma in a patient with ocular melanocytosis is about 1 in 400— significantly greater than the approximate 6-per-million risk of the general population.

Nevus

Nevocellular nevi of the conjunctiva are hamartias that arise during childhood and adolescence. A nevus can be junctional, compound, or subepithelial.

PATHOGENESIS Pure intraepithelial nevi are rare except in children, and these junctional nevi may be difficult to distinguish histopathologically from primary acquired melanosis. The subepithelial nevus of the conjunctiva is the equivalent of the intradermal nevus of the skin.

CLINICAL FINDINGS A nevus near the limbus is usually almost flat. Nevi appearing elsewhere on the bulbar conjunctiva, semilunar fold, caruncle, or eyelid margin tend to be elevated. Pigmentation of conjunctival nevi is variable; they may be light tan to brown or amelanotic (Fig 8-9). A subepithelial nevus often has a cobblestone appearance.

Figure 8-9 Amelanotic conjunctival nevus. (Courtesy of Kathryn Colby, MD, PhD.)

Small epithelial inclusion cysts occur within about half of all conjunctival nevi, particularly the compound or subepithelial varieties. Secretion of mucin by goblet cells in the inclusion cysts can cause a nevus to enlarge, producing a false impression of malignant change. Cellular proliferation may induce secondary lymphocytic inflammation. Rapid enlargement can occur at puberty, giving rise to a clinical impression of conjunctival melanoma. When inflamed, an amelanotic, vascularized nevus may resemble an angioma, or it may be misdiagnosed as chronic conjunctivitis. Table 8-3 compares the various pigmented lesions of the conjunctiva.

MANAGEMENT Conjunctival nevi rarely become malignant and can be followed every 6–12 months with serial photography or detailed slit-lamp drawings that include dimensional measurements. Excisional biopsy should be performed on lesions that change. A biopsy should also be performed for pigmented lesions on the tarsal conjunctiva, the caruncle, or the plica semilunaris or in the fornix, as nevi are rare in these locations.