acanthosis nigricans
Last reviewed 06/2021
Acanthosis nigricans is a rare condition characterised by a brown to black velvety papillomatous hyperplasia of the epidermis with intense hyperpigmentation most prominent in axillary, inguinal, infra-mammary and neck creases. In advanced forms, there may also be veruccous patches on the knuckles and other extensor surfaces, and hyperkeratoses of the palms - 'tripe palms' - and soles.
In contrast to other types of hyperpigmentation - for example secondary to Addison's disease - the areas of pigmentation are discrete.