Abstract

Introduction

Acanthosis Nigricans is characterised by darkening (hyper pigmentation) and thickening (hyperkeratosis) of the skin, occurring mainly in the folds of the skin in the armpit (axilla), groin and back of the neck. It can occur with endocrine diseases such as diabetes mellitus, thyroid disorders, Cushing disease, PCOD, underlying malignancies, certain drugs, and as a genetic disorder. It is most common in people who have insulin resistance those whose body is not responding correctly to the insulin that they make in their pancreas. It is not a skin disease per se but a cutaneous sign of an underlying disorder.

Neck is the most commonly affected area. More than ninety percent of peoples AN have neck involvement. Axilla is the second most common area involved. There are two important types of acanthosis nigricans: benign and malignant. Although it is classically described as a sign of internal malignancy, this is very rare. Benign types, sometimes described as ‘pseudoacanthosis nigricans’ are much more common which is related to obesity. AN is common in some populations and its prevalence changes with different races and is more prevalent in people with darker skin pigmentation.

Acanthosis nigricans (AN) is a dermatosis characterized by velvety, papillomatous, brownish-black, hyperkeratotic plaques, typically appears on the intertriginous areas and neck. A although it may be associated with  internal malignancy, it is more common with obesity and insulin resistance and hence allows for diagnosis of related disorders including type 2 diabetes, the metabolic syndrome, and polycystic ovary syndrome in asymptomatic cases also. Early recognition of these conditions is very helpful for prevention of disease progression and related complications. The exact incidence of acanthosis nigricans is unknown. In a study of unselected population of 1412 children, the changes of AN were present in 7.1%.