Melanoma of the skin is a cancerous growth that has the potential to spread (metastasize) to other parts of the body. Melanoma starts from melanocytes (cells that make melanin, which gives skin, hair and eyes their colour). In women, the most common place for melanoma to occur is on the legs. In men, the most common place for melanoma to occur is on the chest or back. Rarely, melanoma can start in parts of the body other than the skin, such as the mucous membranes or the eye.
There are 4 main types of melanoma of the skin:
Superficial spreading melanoma is the most common type of melanoma of the skin. It accounts for 70% of all melanomas. It most commonly occurs on the legs in women and on the chest or back in men. Superficial spreading melanoma is generally slow growing at first. It tends to grow outward (radial growth) and spread out across the surface of the skin. This type of melanoma doesn’t usually spread to other parts of the body until it begins to grow downward (vertical growth).
Superficial spreading melanoma is usually flat and irregular in shape. It varies in colour, usually with different shades of black and brown.
Nodular melanoma is the second most common type of skin melanoma. It can grow more quickly than other types of melanoma. It is most commonly found on the chest, back, head or neck. Nodular melanoma tends to grow downward (vertical growth) rather than outward (radial growth) and can spread quickly if not removed.
Nodular melanoma usually starts as a raised area that is dark blackish-blue or bluish-red. However, some nodular melanomas are flesh-coloured.
Lentigo maligna melanoma is usually found in older people. It occurs most commonly in areas of high sun exposure, such as the face and neck. It is usually slow growing.
Lentigo maligna melanoma usually appears as a large, flat abnormal skin area. It is usually tan to brown in colour and varies in colour throughout.
Acral lentiginous melanoma is a rare type of melanoma that occurs on the palms of the hands, soles of the feet or under the nails. Like nodular melanoma, acral lentiginous melanoma is usually aggressive and changes rapidly from radial to vertical growth.
Mucosal lentiginous melanoma is a rare type of melanoma that occurs in the mucous tissue that lines the respiratory, gastrointestinal and genitourinary tracts. It can occur on mucous tissue anywhere in the body, including internal organs, the nose, mouth, pharynx, esophagus, cervix, vulva, vagina, penis or rectum.
Intraocular melanoma is a type of melanoma that starts in the eye.