ABSTRACT
Acanthosis nigricans (AN) and acrochordons have been commonly associated with insulin resistance (IR) and the metabolic syndrome. AN can be seen in other disorders, including Cushing syndrome, polycystic ovaries, thyroid diseases, hirsutism, Addison disease, acromegaly, genetic syndromes, and malignancy. The mechanism of IR is complex, but essentially, it is a disorder where target cells in the body do not respond to circulating insulin. This leads to compensatory hyperinsulinemia, which causes an upregulation of insulin-like growth factor type 1 (IGF-1). Increased IGF-1 leads to keratinocyte and fibroblast proliferation, which is clinically apparent as AN and acrochordons. Malignancy-associated AN is believed to be due to stimulation of keratinocytes by secreted factors from the associated tumor, including transforming growth factor-α (TGF-α).
