There are four major types of melanoma. Superficial spreading melanoma, or SSM, is the most common type in the United States. It accounts for about 70 percent of all diagnosed melanoma cases. This type can develop at any age and occurs slightly more often in women than men. SSM is the leading cause of death from cancer in young adults. These melanomas are generally flat and irregular in shape and color, with different shades of brown and black. Superficial spreading melanoma may appear at any location on the body and is most common in Caucasians. It’s characterized as a thin melanoma, which means it has a tendency to spread out over the top of the skin’s surface.
Nodular melanoma, or NM, may start as a bump or raised area that is dark blackish-blue or bluish-red, although some nodular melanomas do not have any color. It’s the most serious and life-threatening form of skin cancer. NM is characterized as a thick melanoma, or tumor, which means it penetrates and grows deeper into the skin. Generally, nodular melanoma has already invaded the skin when it’s first diagnosed. It’s normally seen on the arms, legs, upper torso, neck, head or scalp.
Nodular melanoma is less common than other types of melanoma and accounts for only about 15 percent of melanoma cases. This skin cancer commonly affects people after age 50. It’s important to remember that nodular melanoma generally develops in normal skin, and not in existing lesions. NM is also characterized by rapid growth.
Another type of melanoma is called lentigo maligna melanoma, or LMM. It accounts for about 10 percent of the melanomas diagnosed in the United States. This type usually occurs in the elderly and is most common in sun-damaged skin on the face, neck, arms and legs. It’s similar to superficial spreading melanoma because the abnormal skin areas are typically large, flat, and tan with areas of brown. Lentigo maligna tend to have an irregular border, uneven coloring and may be slightly raised. LMM is also characterized as a thin melanoma.
Finally, acral lentiginous melanoma, or ALM, is the least common form of melanoma. In the United States, it accounts for about five percent of all diagnosed melanomas. It’s the most common form of melanoma in Asians and African Americans, accounting for 50 percent of melanomas in these skin types. ALM is sometimes referred to as a “hidden melanoma” because the lesions develop on parts of the body not easily examined or not thought necessary to examine. It usually develops on the palms of the hands, soles of the feet, under the nails or in mucous membranes that line the mouth, nose and female genitals.