The normal precursor of malignant melanoma is the melanocyte, a cell of neural crest origin. In their embryological state, neural crest cells are unique in that they dissociate from the notochord on days 10–14 and migrate out, or “metastasize,” to numerous sites of the body as their new “homes.” These cells are known as “argentaffin cells” and
include the melanocytes. Of interest is that melanocytes can also accumulate abnormally in clusters as nevi and thereafter reside in the lower stratum of the epithelium just above the level of the dermis (and occasionally in the dermis). The most important function of these melanocytes either singularly or in clusters is to manufacture melanin, a pigmented biopolymer that is distributed throughout the skin to protect the host from the damage of ultraviolet radiation. Indeed, the amount of pigmentation sets the background of racial groups in human beings. It is estimated that the number of melanocytes in the body is relatively constant between different racial groups, although the production of melanin varies dramatically from one race to the other. Melanocytes in lightly colored skin make the least amount of melanin, whereas melanocytes in darker skin make larger amounts of melanin, which provides significantly greater protection against the direct ultraviolet radiation at the equator and its subsequent photocarcinogenesis.