Most types of melanoma begin in the skin and are called cutaneous melanoma. But melanoma can also begin in other organs. It can begin in the eye, where it is called ocular melanoma. This type can cause partial or total vision loss and often spreads to the liver if not diagnosed early.
Cutaneous melanomas are classified into these subgroups:
Superficial spreading. This is the most common form, making up about 70 percent of all cutaneous melanomas. These often grow along the skin for a long time before invading the skin more deeply. They often have irregular shapes and are several shades of brown or other colors, such as black, blue, or red.
Nodular. These are often black, dome-shaped lesions. They tend to grow into deeper skin layers quickly. [Note: Some pathologists no longer use the terms superficial or nodular, but describe the growths in terms of vertical growth and ulceration.]
Acral lentiginous. These are found on the palms of your hands, soles of your feet, under a nail (subungual), or on mucous membranes, such as the mouth, rectum, or vagina (mucosal). This is the most common type found in people with naturally darker skin.
Lentigo maligna. Common in older people, these lesions are typically flat and large, spreading widely along the surface of the skin. They often begin as benign lesions on the face or other sun-exposed area.
Desmoplastic or neurotropic. These melanomas show up as small nodules on the skin, which are nonpigmented (light in color). They can travel and grow along nerves in the skin and can cause the development of fibrous tissue.
Amelanotic melanoma. These melanomas are often pink or flesh-colored. They are variants of the more common melanomas because they don’t make pigment. As a result, they can be mistaken for a pimple or nonmalignant lesion.