Melanoma is the eighth most common malignancy in the United States and its incidence continues to rise at a rate faster than that of any other human cancer. In the 1930's the survival rate for melanoma was abysmally low, but now 5 and 10 year survival rates are well over 80%. There are 4 major types of melanoma that have distinct characteristics and potential for metastasis.
Lentigo Maligna Type
This type of melanoma is more commonly found on the head and neck region. It begins as a small, asymmetric pigmented patch that has irregular borders and color variations throughout the lesion. Over time the patch gets larger and retains its asymmetry, irregular borders, and color variations. This type of melanoma may remain flat and confined to the epidermis for months to many years, but at some point will penetrate into the deeper levels of skin, increasing the potential for metastases.
Superficial Spreading Type
This type of melanoma is more commonly found on the trunk, upper arms, and thighs, and is the most common form of melanoma in white races. It begins a small pigmented macule that is asymmetric, has irregular borders, and has color variations. This type of melanoma remains in the flat phase for a shorter period of time than the lentigo maligna type before it penetrates into the deeper levels of the skin.
This type of melanoma can occur on any skin surface but is found more commonly on the trunk, upper arms, and thighs. The nodular type of melanoma has a very short flat phase before it forms a raised nodule and penetrates into the deeper levels of the skin. This type of melanoma may ulcerate and present as a non-healing skin ulcer.
This type of melanoma is more commonly found on the hands, feet, and nail beds. It is seen in all races, but is most frequently found in dark-skinned races. It is similar to the lentigo maligna and superficial spreading type in that it has a relatively long flat phase before it penetrates into the deeper levels of the skin.