The most common type of melanoma is skin (cutaneous) melanoma. There are two categories of skin melanoma:
- In situ melanoma is confined to the epidermis or upper layer of the skin. It will not spread once the lesion has been removed.
- Invasive melanoma has advanced into the deeper layers of the skin called the dermis and the subcutis. In general, the thicker the melanoma is, the more likely it is to invade other parts of the body. When melanoma metastasizes, or spreads to other parts of the body, it commonly involves the lymph nodes, lungs, liver, brain, bones, and digestive tract, but can involve any part of the body.
Melanoma in the eyes
Less commonly, melanoma can affect the eyes. Melanoma can affect many parts of your eyes, including:
• The layer of the eye between the retina and the white outer layer of the eye called the choroid. This type of melanoma is called uveal melanoma which is the most common type of eye melanoma.
• The eyelids
• The clear mucosal surface of the eye called the conjunctiva, which covers the eye’s surface and the inside of the eyelids. This type of melanoma is called conjunctival melanoma.
Melanoma can also arise from the mucosal surfaces of the body. Slightly over half of all mucosal melanomas begin in the head and neck region, approximately one quarter of mucosal melanomas arise from the anorectal region, and another 20% arise from the female urogenital tract. Melanomas originating in mucosal surfaces lining the esophagus, gallbladder, bowel, conjunctiva, urethra, and other sites are far less common.