Acanthosis nigricans: A new cutaneous sign in severe atopic dermatitis andDown syndrome

Acanthosis nigricans (AN) occurs associated with many different systemic di seases, such as endocrine disorders and internal malignant neoplasms. To ou r knowledge, the association of AN with severe atopic dermatitis (AD) or Do wn syndrome has not been described before. This 82-month retrospective stud y included 1038 patients: AN was present in 4.9% of,atopic patients and 50. 9% of subjects with Down syndrome. AN was more frequent in patients with se vere AD and in 100% of cases of hand dermatitis and juvenile plantar dermat osis, located on the interphalangeal and metacarpophalangeal joints, wherea s in Down syndrome other flexures were also affected. The pathogenesis of A N in AD is unknown, but in Down syndrome it seems to be related to obesity. Possible insulin resistance underlyng the pathogenesis of AN in these pati ents is still unknown.