PATHOGENESIS

Conjunctival melanomas may arise from PAM (70%) or nevi (5%) or may arise de novo (25%). Intralymphatic spread increases the risk of metastasis. In rare cases, an underlying ciliary body melanoma can extend through the sclera and mimic a conjunctival melanoma.

CLINICAL PRESENTATION

Although conjunctival melanomas can arise in palpebral conjunctiva, they are most commonly found in the bulbar conjunctiva or at the limbus (Fig 12-12A). The degree of pigmentation is variable; approximately 25% of conjunctival melanomas are amelanotic. Recurrent melanomas are often amelanotic, even if the primary tumor was pigmented (Fig 12-12B). Because heavy vascularization is common, these tumors may bleed easily. They grow in a nodular fashion and can invade the globe or orbit. Poor prognostic indicators include

Figure 12-12 A, Multifocal, partially pigmented malignant melanoma of the limbal conjunctiva. B, Recurrent amelanotic conjunctival melanoma. The primary tumor was pigmented. C, Small conjunctival melanoma in the inferior fornix.

(Courtesy of Kathryn Colby, MD, PhD.)

• location in the palpebral conjunctiva, caruncle, or fornix (Fig 12-12C)

• invasion into deeper tissues

• thickness >1.8 mm

• involvement of the eyelid margin

• pagetoid or full-thickness intraepithelial spread

• lymphatic invasion

• mixed cell type

Conjunctival melanomas may metastasize to regional lymph nodes, the brain, lungs, liver, and bone.

MANAGEMENT

Ocular surface lesions worrisome for melanoma should be treated expeditiously using the paradigm described at the beginning of the chapter. Sentinel lymph node biopsy has been advocated by some authors but has not been widely adopted. Orbital exenteration is occasionally performed for advanced disease when local excision or enucleation cannot completely excise the tumor (when metastases have been excluded) or as palliative treatment for advanced, aggressive tumors that cannot be controlled locally. The role of adjunctive radiotherapy has not been determined.

Conjunctival melanoma has a high rate of recurrence (more than 50%). Patients with a history of conjunctival melanoma thus require lifelong, close ophthalmic follow-up and should be counseled to contact their physician immediately should they notice any changes in the involved eye. Conjunctival melanomas are potentially deadly tumors. In one study, metastasis was detected in 26% of patients, and death occurred in 13% of patients 10 years after surgical excision. Melanomas arising de novo (ie, not from preexisting nevi or PAM), tumors not involving the limbus, and residual involvement at the surgical margins are factors associated with an especially poor prognosis.

Manjandavida FP, Lally SE, Shields JA, Shields CL. Conjunctival melanoma: what you should know. [American Academy of Ophthalmology Annual Meeting Video]. San Francisco: American Academy of Ophthalmology; 2013. Available at www.aao.org.

Savar A, Ross MI, Prieto VG, Ivan D, Kim S, Esmaeli B. Sentinel lymph node biopsy for ocular adnexal melanoma: experience in 30 patients. Ophthalmology. 2009;116(11): 2217–2223.

Shields CL, Markowitz JS, Belinsky I, et al. Conjunctival melanoma. Outcomes based on tumor origin in 382 consecutive cases. Ophthalmology. 2011;118(2):389–395.

Shields JA, Shields CL. Conjunctival melanocytic lesions. In: Eyelid, Conjunctival, and Orbital Tumors: An Atlas and Textbook. 3rd ed. Philadelphia: Wolters Kluwer; 2016:307–348.

Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.