Acanthosis nigricans Acanthosis nigricans is a rash of velvety hyperpigmentation seen most commonly in the axillae. It is often associated with skin tags & may occur in other sites such as neck, groin , mouth, hands & perianal region. Histologically, it shows hyperkereatosis, acanthosis & papillomatosis. 1, Pseudo- acanthosis nigricans is most commonly seen in association with obesity & endocrine disorders such as diabetes & Cushing’s disease. It is thought that friction & maceration of the flexures plays a role in the disorder’s etiology. 2. Congenital acanthosis nigricans is inherited in an autosomal dominant manner. The rash often appears before puberty & may be associated with mental retardation & neurofibromatosis. 3. True acanthosis nigricans :is rare, it presents in non-obese adults & is always associated with cancer It is a poor prognostic sign usually associated with disseminated disease. Mouth & hand (Triple palm ) lesions are characteristic.

Acanthosis nigricans

Acanthosis nigricans Oral acanthosis nigricans N.Eng. J. Med. 2OO7:357

Acanthosis nigricans Classification A. Schwartz classification: Schwartz,R.A. :J. Am. Academy of Dermat. 31: 1, 1994 @ Benign acanthosis nigricans @ Acanthosis nigricans associated with obesity @ syndromic acanthosis nigricans @ Malignant acanthosis nigricans @ Acral acanthosis nigricans. @ Unilateral acanthosis nigricans @ Drug induced acanthosis nigricans @ Mixed acanthosis nigricand B. James et al. Andrews “Diseases of the skin” Clinical dermatology Saunders 2OO5 1Oth edition @ Acral acanthotic anomaly @ Acanthosis nigricans type I ( in association with malignancy) @ Acanthosis nigricans type II ( Familial acanthosis nigricans) @ Acanthosis nigricans type III ( Acanthosis nigricans associated with obesity, insulin resistant states & endocrinopathy.

Acanthosis nigricans Classification C. Judge et al. Rook’s textbook of dermatology Blackwell seventh edition 2OO4: @ Inherited forms of acanthosis nigricans @ Benign acquired acanthosis nigricans @ HAIR -AN syndrome: The triad of hyperandroginism, insulin resistance & acanthosis nigricans in women is known as HAIR-AN syndrome @ Autoimmune acanthosis nigrican @ Drug – induced acanthosis nigricans @ Malignancy associated acanthosis nigrican @ Tripe palm: velvety rugose thickening of the palm is almost always associated with internal malignancy. By contrast, familial keratoderma associated with malignancy is compact & non- rugose. @ Nevoid acanthosis nigricans