Primary malignant melanoma of the conjunctiva

• Conjunctival malignant melanoma is a pigmented lesion of the ocular surface.
• It is an uncommon and accounts for about 2% of all the malignant melanomas.

Invades the eye

• It is a potentially devastating tumor that may invade the local tissues of the eye, spread systemically through lymphatic drainage and hematogenous spread, and recur in spite of treatment.
• Conjunctival malignant melanoma (CMM) is a rare but potentially life-threatening cancerous growth of the eye. It arises from melanocytes located amongst the basal cells of the conjunctival epithelium.

Epidemiology

• Overall incidence is between 0.24 to 0.8 cases of CMM per million, based on population data from the national registries of Finland, Sweden, Denmark, the Netherlands and the United States over several decades .
• Incidence is increasing .
• Over a 27-year period between 1973 and 1999, the age-adjusted incidence of CMM in the United States increased by 101%, and by 295% in white males older than 60.

Risk Factors

• The risk factors for CMM are not well understood. While there are known risk factors for cutaneous melanoma, including family history, fair skin and hair, high density of freckles , UV light exposure especially during childhood , and genetic syndromes such as familial melanoma syndromes, xeroderma pigmentosum, Hodgkin lymphoma and hereditary retinoblastoma, the risk factors for CMM are not yet established.

Malignant melanoma

Signs and symptoms

• Conjunctival melanoma commonly presents as a thickened, raised, pigmented lesion with prominent feeder vessels and surrounding areas of melanosis.
• It is usually unilateral and presents in adulthood.
• Most patients simply complain of noticing a pigmented spot but on rare occasions, the tumor can be associated with ocular pain and irritation
• The most common location is on the bulbar conjunctiva (60-92%) most likely because this area is directly exposed to sunlight.

Diagnosis

• The diagnosis of CMM is usually made by careful clinical examination and slit lamp biomicroscopy.
• Clinical examination should include a thorough history (age, symptoms, sun exposure, evolution of lesion, previous cancers, symptoms, and review of old photographs) and physical examination (lymph node palpation, gross examination of ocular surface, changes in eyelids and adjacent skin).
• On slit lamp, the examiner should inspect the ocular surface carefully for pigment, nodularity, and feeder vessels, remembering to examine intertriginous areas such as the fornix and tarsal conjunctiva by everting both the lower and upper eyelids.
• The presence of pigment, particularly on the tarsal conjunctiva should heighten suspicion for CMM.
• The anterior chamber should also be examined and a dilated fundus examination performed to inspect the interior surfaces of the eye.
• Slit lamp photographs should be taken to document the size and extent of the lesion.

Differential diagnosis

• Differential diagnosis includes the progenitors of CMM: PAM and conjunctival nevi.
• Like CMM, PAM is typically unilateral but presents as a flat, asymmetric, noncystic, pigmented patch on the conjunctiva or cornea.
• The lesion may be multifocal
• Other differential diagnoses include local extension of uveal melanoma or melanocytoma, and distant metastasis of cutaneous melanoma.
• An excisional biopsy is preferred over concerns of tumor cell seeding.
• Histological sections should be made perpendicular to the epithelial surface to allow measurements of tumor thickness.
• Specimens are oftentimes bleached because the melanin granules can obscure cell morphology and underlying architecture, and interfere with antibody-antigen interaction during analysis by immunohistochemistry
• Histopathology remains the gold standard for definitive diagnosis of CMM.
• It provides unparalleled resolution and the ability to visualize all layers of tissue.
• CMM can sometimes be difficult to distinguish from nevi, and excised tissue may miss lesions present elsewhere.

Treatment

• Management options are based on a number of case reports and limited case series, as the rarity of this tumor has made it difficult to conduct clinical trials to determine the best therapy.
• The current standard of care is wide local excision, followed by double freeze-thaw cryotherapy to the margins. This is often followed by a variety of adjuvant therapies in order to prevent recurrence and metastasis. We have developed an algorithm for approaching the management of CMM.
• The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition.
• Aldesleukin (Brand name: Proleukin)Treatment of adults with metastatic melanoma.

External links

• Review article

Primary malignant melanoma of the conjunctiva Resources
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NIH genetic and rare disease info

• NIH info on Primary malignant melanoma of the conjunctiva

Primary malignant melanoma of the conjunctiva is a rare disease.