This is due to differences in pigmentation, as well as to differences in tissue responses to inflammation and injury. This module reviews these differences, as well as some disorders which are unique to, or more common in, darkly pigmented skin. We will also review several common skin disorders which have unique manifestations in darker skin.
Skin color is determined by the size, melanization and distribution of melanosomes.
Melanosomes are the melanin synthesizing organelles which are present in melanocytes and are distributed to the epidermal keratinocytes. Black skin and white skin have the same number of melanocytes. However, melanosomes in dark skin are larger, more highly melanized, and are distributed singly and in small groups of two to three throughout the keratinocytes in the epidermis. Melanosomes in white skin are smaller and are distributed in larger clusters, usually variable in size in complexes of five to seven.