What is Conjunctival Melanoma?
The conjunctiva is the clear tissue that covers the white part of the eye, as well as the inside of the eyelids. Conjunctival melanoma often appears as a raised tumor and may contain little or no pigment. Conjunctival melanoma most commonly occurs in the bulbar conjunctiva — the mucous membrane that covers the outer surface of the eyeball.
Conjunctival melanoma is very rare, making up only 2% of all eye tumors and 0.25% of all melanomas. According to registry data from five countries, overall incidence is between 0.24 to 0.8 cases per million. However, incidence appears to be increasing, just as incidence rates are increasing in melanoma of the skin, suggesting a possible association between conjunctival melanoma and ultraviolet (UV) exposure.
Diagnosing Conjunctival Melanoma
A conjunctival melanoma diagnosis usually begins with a thorough examination of the eye and all conjunctival surfaces, including the inside of the eyelids. It is recommended that photographs be taken before a biopsy is taken. This allows the doctor to properly document the extent of the melanoma and may assist in planning for treatment and follow-up.
A biopsy of the tumor and examination of the tissue under a microscope will rule out or diagnose conjunctival melanoma. If conjunctival melanoma is diagnosed, the extent of disease and treatment plan should be discussed with a trained ocular oncologist.
Primary Management and Treatment
Surgery is the most common type of treatment for conjunctival melanoma. Enucleation, or removal of the eye, has been used for the treatment of extensive conjunctival melanoma. However, data does not currently indicate that this improves overall survival. Therefore, wide local excision and biopsy is the current standard approach.
Excision is often followed by one or more types of adjuvant therapy in an effort to prevent the melanoma from spreading, or metastasizing. Types of adjuvant therapies could include cryotherapy (using freezing or near-freezing temperatures), topical chemotherapy or radiation therapy.
In-depth descriptions of common ocular melanoma treatments can be found here.
Long-term follow-up of patients with conjunctival melanoma is recommended in order to detect recurrences or metastatic disease. Patients should be monitored for recurrence by a trained ocular oncologist.
Prognosis and Metastases
Conjunctival, uveal and cutaneous melanoma are distinct from one another. Therefore, they each require different treatment strategies. While there is no standardized treatment for uveal or conjunctival melanoma, significant advances have been made in our understanding of these rare melanoma subtypes. This has led to novel targeted therapy and immunotherapy approaches.
When conjunctival melanoma spreads, it often behaves more closely to cutaneous melanoma in that it usually spreads through the lymph nodes. From there, it has the ability to spread to the lungs, liver, soft tissues, bone and brain. When uveal melanoma spreads, it most often spreads to the liver and doesn’t usually spread through the lymph nodes.
Because conjunctival melanoma usually spreads through the lymph system, sentinel lymph node biopsy (SLNB) may be considered and discussed with your treatment team. Risk factors for metastasis include tumor thickness, ulceration and mitotic rate. These are known risk and prognostic factors for cutaneous melanoma and were incorporated into staging criteria.
Metastatic Treatment of Conjunctival Melanoma
Although there are currently no FDA-approved systemic treatments for conjunctival melanoma that has metastasized, some clinicians recommend treatment with therapies that have been FDA-approved for cutaneous melanoma. In addition, ongoing clinical trials may give patients access to systemic agents before they are approved.
- Immunotherapy – A type of systemic treatment given to activate a person’s immune system so that it will destroy melanoma cells within the body. Several immunotherapies are FDA-approved for cutaneous melanoma and some are being studied in ocular melanoma.
- Targeted Therapy – A form of treatment in which drugs are developed with the goal of destroying cancer cells while leaving normal cells intact. These drugs are designed to interfere with the specific molecules, genetic mutations in the tumor itself, that are driving the growth and spread of the tumor. For example, the BRAF mutation, which is found in about 50% of cutaneous melanomas, is also present in about 30% of conjunctival melanomas. Therefore, some clinicians may recommend targeted therapy for the treatment of conjunctival melanoma in which the BRAF mutation has been found.
- Chemotherapy – Overall, chemotherapy has not been shown to be effective for ocular melanoma. However, it still may be recommended in some cases.
- Clinical Trials – Clinical trials should be explored as a treatment option for anyone diagnosed with conjunctival melanoma. Learn more about trials here!