What is Acanthosis nigricans?

symmetrical, brown, velvety plaques that are often found on the neck, axilla and groin

What are the main causes of Acanthosis nigricans?

• type 2 diabetes mellitus
• gastrointestinal cancer
• obesity
• polycystic ovarian syndrome
• acromegaly
• Cushing's disease
• hypothyroidism
• familial
• Prader-Willi syndrome
• drugs (combined oral contraceptive pill, nicotinic acid)

What is the pathophysiology of Acanthosis nigricans?

insulin resistance → hyperinsulinemia → stimulation of keratinocytes and dermal fibroblast proliferation via interaction with insulin-like growth factor receptor-1 (IGFR1)