Acanthosis nigricans is a skin condition characterised by a velvety papillomatous overgrowth of the epidermis

Aetiology

• 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

Pathophysiology

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

Clinical features

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

Management

• Management of underlying disease
• Patient information