Epidemiology

Acanthosis nigricans (AN) is most often associated with obesity and insulin resistance.[2][5][6]​​​[7]​ It is the most common dermatological manifestation of obesity.[15] As rates of obesity rise globally, so does the incidence of AN.​[1]​​ AN is very common in dark-skinned populations throughout the world, but is rare in white people.[16] The prevalence of AN varies from 7% to 74%, depending on the type of AN and on patient factors; including age, race, and presence of obesity and associated endocrinopathy.[1]​ A study of 1133 patients in southwest US reported the prevalence of AN as 21% in adults and 17% in children; people with type 2 diabetes mellitus were almost twice as likely to have AN compared with people without diabetes.[17]​ Children with AN are up to 4.2 times as likely to have hyperinsulinaemia than those without.​[7][18]​​ In one study of 618 young people, AN was found in 62% of people with a BMI >98th percentile and was more common in ethnic minorities, with 23% of Hispanic, 19% of black, and 4% of white people affected.[5]

Malignant AN is rare, although the exact incidence is unknown. It is reportedly present in 2 out of 12,000 patients with cancer.[19] It is reported most often in adults over the age of 40 years and has no sex or racial predilection.[8]

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