Melanoma of the eyelid

A rare but serious malignancy of the eyelid or ocular surface

Melanoma arises from melanocytes, the pigment-producing cells found throughout the skin and on various mucosal surfaces. On and around the eyelid, melanoma can develop in two distinct anatomical locations: the skin of the eyelid itself (cutaneous eyelid melanoma), or the conjunctiva, the transparent tissue that lines the inside of the eyelids and covers the white of the eye (conjunctival melanoma).

Cutaneous eyelid melanoma represents approximately 1% of all skin melanomas. It is rare, but the eyelid skin is anatomically close to the orbit and to critical structures, which makes management more complex than melanoma elsewhere on the body. Conjunctival melanoma is even rarer, accounting for around 2 per million of the population per year.

Both forms are serious. Both require early diagnosis and specialist management. Both are more successfully treated when caught before spread has occurred.

Cutaneous and conjunctival melanoma are distinct conditions

Cutaneous eyelid melanoma

This arises from the melanocytes of the eyelid skin and behaves similarly to melanoma elsewhere on the face, though the proximity to the orbit and the lymphatic drainage of the eyelid to the parotid and cervical lymph nodes gives it some anatomical peculiarities that influence staging and surgery. The lower eyelid is more commonly affected than the upper.

Lentigo maligna melanoma, a subtype that arises from a precursor lesion called lentigo maligna (also known as Hutchinson's melanotic freckle), is the most common subtype on the eyelid skin. Lentigo maligna appears as a slowly expanding, irregularly pigmented patch on sun-damaged skin, most often in older patients. It can be present for years before invasive melanoma develops.

Conjunctival melanoma

This arises from the conjunctiva, the transparent tissue covering the white of the eye and lining the inside of the eyelids. It typically presents as a pigmented lesion on the conjunctival surface, often arising from a pre-existing area of primary acquired melanosis (PAM), which is a flat, diffuse pigmentation of the conjunctiva. A pigmented spot on the white of the eye that has been present for years and is now growing should be assessed urgently by an ophthalmologist.

Conjunctival melanoma can spread via the lymphatics to regional nodes, and via the bloodstream to the liver, lungs, and brain. Survival is closely linked to stage at diagnosis.

What to look for: the ABCDE criteria and beyond

The standard ABCDE criteria for melanoma apply to eyelid skin melanoma and provide a useful checklist: Asymmetry (one half of the lesion does not mirror the other), irregular Border, variation in Colour (more than one shade, or areas of black, brown, pink, or white within the same lesion), Diameter greater than 6 mm, and Evolution (recent change in size, shape, colour, or a new symptom such as bleeding or itching).

On the eyelid, two additional features are worth noting. First, amelanotic (non-pigmented) melanoma exists, where the lesion appears flesh-coloured or only faintly pink. This is rare but can be missed precisely because the absence of pigment makes it less recognisable as a melanocytic lesion. Second, a nodular melanoma can arise rapidly as a firm, dark nodule without the gradual expanding phase typical of superficial spreading melanoma. Nodular melanoma grows quickly and can ulcerate.

For conjunctival melanoma, the key feature is a pigmented lesion on the conjunctival surface that is growing, has nodular areas (raised above the surface), or is accompanied by dilated, feeding blood vessels. The onset of symptoms such as a foreign body sensation, discharge, or redness in a patient with a known conjunctival pigmented lesion should prompt urgent review.

Sun exposure, skin type, and ocular melanocytosis

For cutaneous eyelid melanoma, the risk factors are consistent with those for skin melanoma elsewhere: fair skin, a tendency to burn, a history of significant sun exposure or sunbed use, a large number of moles (naevi), a history of previous melanoma, and a family history of melanoma.

Lentigo maligna, the common precursor to eyelid melanoma in older patients, is closely associated with chronic cumulative UV exposure. It is most common on the faces of fair-skinned individuals over the age of sixty who have spent significant time outdoors over their lifetime.

For conjunctival melanoma, ocular melanocytosis (a congenital, diffuse pigmentation of the uveal tract and episclera) is an important risk factor. Primary acquired melanosis (PAM) of the conjunctiva with atypia on histology is also a recognised precursor lesion. Patients known to have PAM with atypia are followed regularly in specialist clinics.

Staging, excision, and specialist multidisciplinary management

Both cutaneous eyelid melanoma and conjunctival melanoma are managed by specialist multidisciplinary teams that include oculoplastic surgeons, ocular oncologists, dermatological oncologists, and head and neck surgeons, depending on the extent and stage of disease.

Staging

Staging involves assessment of the primary tumour (Breslow depth for cutaneous melanoma, tumour extent for conjunctival melanoma), imaging of the regional lymph nodes, and systemic imaging to look for distant metastasis. Sentinel lymph node biopsy is usually recommended for cutaneous eyelid melanomas of appropriate thickness.

Surgical treatment

Excision with wide histological margins is the primary surgical treatment for both types. For cutaneous eyelid melanoma, wide local excision with Mohs surgery or staged excision is followed by eyelid reconstruction by an oculoplastic surgeon. For conjunctival melanoma, excision of the involved conjunctiva with adjuvant cryotherapy to the margins, and sometimes topical mitomycin-C, is the standard approach. More extensive conjunctival involvement may require adjuvant radiotherapy.

Systemic treatment

For metastatic or high-risk melanoma, systemic treatments including immunotherapy (checkpoint inhibitors such as pembrolizumab and nivolumab) and targeted therapy (for BRAF-mutated tumours) have transformed outcomes in recent years. These are prescribed and managed by medical oncologists.