Types of melanoma skin cancer
Melanoma skin cancer can grow into and destroy nearby tissue. It can also spread (metastasize) to other parts of the body. Melanoma skin cancer is also called cutaneous melanoma and malignant melanoma of the skin.
There are 4 main types of melanoma skin cancer – superficial spreading, nodular, lentigo maligna and acral lentiginous.
Superficial spreading melanoma
Superficial spreading melanoma is the most common type of melanoma skin cancer. It makes up about 70% of all melanoma skin cancers.
Superficial spreading melanoma tends to grow outward (called radial growth) and spread across the surface of the skin. But it can also start to grow down into the skin (called vertical growth). It is often flat and thin (less than 1 mm thick) with an uneven border. It varies in colour and may have different shades of red, blue, brown, black, grey and white. Sometimes superficial spreading melanoma starts from a mole that is already on the skin.
Superficial spreading melanoma usually develops on the central part of the body (trunk), arms and legs. It tends to happen on the back in men and the legs in women.
Nodular melanoma is the second most common type of melanoma skin cancer. It makes up about 15% to 20% of all melanoma skin cancers.
Nodular melanoma grows down into the skin. It grows and spreads more quickly than other types of melanoma skin cancer. It is a raised growth that sticks out from the skin (polypoid). The growth may be shaped like a mushroom with a stem or stalk (pedunculated). It is usually black, but sometimes can be red, pink or the same colour as your skin.
Nodular melanoma usually develops on the face, chest or back. It can be found on areas of skin not exposed to the sun.
Lentigo maligna melanoma
Lentigo maligna melanoma most often develops in older people. It makes up about 10% to 15% of all melanoma skin cancers.
Lentigo maligna melanoma usually appears as a large, flat tan or brown patch with an uneven border. It tends to get darker as it grows and has many shades of brown or black. It often starts from an in situ tumour called lentigo maligna, which is an early form of the growth only in the top or outer layer of the skin (epidermis). Lentigo maligna melanoma usually grows outward across the surface of the skin for many years before it starts to grow down into the skin.
Lentigo maligna melanoma usually develops on areas of skin that are regularly exposed to the sun without protection, such as the face, ears and arms.
Acral lentiginous melanoma
Acral lentiginous melanoma is most common in people with dark skin, such as those from African, Asian and Hispanic ancestries. It is not related to being exposed to the sun. It makes up less than 5% of all melanoma skin cancers.
Acral lentiginous melanoma appears as a small, flat spot of discoloured skin that is often dark brown or black. It usually grows outward across the surface of the skin for a long time before it starts to grow down into the skin.
Acral lentiginous melanoma usually develops on the soles of the feet, on the palms of the hands or under the nails. It is often hard to diagnose acral lentiginous melanoma because it’s hard to see abnormal areas on the soles of the feet or under the nails.
Rare types of melanoma
Some rare types of melanoma do not start in the skin. The following types of melanoma are rare.
Mucosal lentiginous melanoma develops on the thin, moist lining of some organs or other parts of the body (mucosa or mucous membrane), such as the nasal passages, mouth, throat (pharynx), rectum, anal canal and vagina. It is not related to being exposed to the sun like most melanoma skin cancers. It is usually diagnosed at a late stage and tends to grow and spread quickly.
Intraocular melanoma starts in the eye. It is the most common type of eye cancer. Find out more about eye cancer (intraocular melanoma).
Desmoplastic melanoma develops in the thick, inner layer of skin (dermis) or the layer of connective tissue that surrounds the mucosa (submucosa). It often appears as a lump that is the same colour as your skin. It tends to grow down into the skin. Desmoplastic melanoma often develops on the head, neck, upper back or areas of the body with a mucosa.
A non-cancerous (benign) growth on the skin that is usually tan, brown or flesh-coloured.
Moles are made up of a cluster of melanocytes (cells that make melanin, which gives skin, hair and eyes their colour). They may be raised or flat.
Also called nevus.
What’s the lifetime risk of getting cancer?
The latest Canadian Cancer Statistics report shows about half of Canadians are expected to be diagnosed with cancer in their lifetime.