a) What is conjunctival melanoma?
Melanomas are tumours which come from pigmented cells in our body. As well as growing on the skin, they can grow on the conjunctiva of the eye. Conjunctival melanoma accounts for 2% of eye cancers. It arises most commonly form primary acquired melanosis, or from a naevus (freckle) already present on the eye. Least commonly it arises on its own; this is known as primary conjunctival melanoma. This cancer can spread to other organs in the body, most commonly, the liver.
b) What does conjunctival melanoma look like?
Conjunctival melanoma looks like an uneven, raised, grey or pink lump growing on white conjunctiva or from a pigmented area on the conjunctiva. This may cause irritation and watering from the eye.
c) What are the risks of getting conjunctival melanoma?
The following increase your risk of developing conjunctival melanoma:
• Having pale skin
• Red or blond hair
• Blue eyes
• Over 50 years of age
• Large number of moles or freckles
• Poor immune system (e.g. HIV)
d) How likely is the conjunctival melanoma to spread around the body?
There are some features that increase the risk of the melanoma spreading. These include:
• Large tumours (large basal diameter, and tumour thickness of greater > 2mm)
• Nodular tumours (rounded and raised)
• Tumour involving the eyelids
• Tumour involving the corner of the eye near the nose (plica or caruncle)
If the tumour has grown on white conjunctiva instead of a pigmented conjunctiva, then the tumour may be more aggressive. Most common place is the liver. A liver ultrasound scan is arranged at your local hospital every year to exclude spread of disease.
e) Will I need any tests?
A biopsy may be required to confirm the diagnosis. If we decide to biopsy we usually remove the whole abnormal area. We may perform CT or MRI scan to make sure the melanoma has not spread to other parts of the body. If the tumour is greater than 2mm thick or growing in the corner of the eye we may need to consider doing a sentinel lymph node biopsy (SLNB). This is where a sample is taken from the glands that drain fluid away from the eye and analysed for tumour cells. These glands are found at the front of the ear and in the neck. This is the first place the tumour spreads to before metastasising around the body. This procedure is carried out in the Queen Elizabeth University Hospital in Glasgow with help from our maxilo-facial surgeon colleagues. If the SNLB detects cancer cells then the glands can be removed with surgery or treated with radiotherapy.
f) What is the treatment of conjunctival melanoma?
Surgery (surgical excision) is performed with or without:
• Mitomycin C (MMC)
Sometimes the tumour is too big or has spread behind the eye. In these situations enucleation may be the best option. If there is involvement of the eyelids or of tissue behind the eye, we may have to consider exenteration. If there is spread of disease to the lymph nodes in the neck, we may have to remove these or treat with radiotherapy.
g) Can the conjunctival melanoma come back after treatment?
Unfortunately the answer to this is yes. Even if the tumour is completely removed there is always a chance of the tumour re-growing in the same place or in other parts of the body. For this reason, we monitor in the clinic after treatment.