Acanthosis nigricans. This is a descriptive term for a velvety or verrucous brown-to-black area of hyperkeratosis. The underarms and the back of the neck are the most common locations, but lesions are also seen on the anterior neck and in the groin. Less commonly, there is involvement in the antecubital and popliteal fossae, on the knuckles, and in other nonflexural areas. Onset may occur during childhood or adulthood. The histologic pattern is that of hyperkeratosis and papillomatosis; the brownish discoloration seems to be caused by these surface changes rather than by any local increase in the amount of melanin. Illustrated here are lesions of acanthosis nigricans on the anterior neck. Acanthosis nigricans can be a risk factor for the development of diabetes in children.
Color Atlas of Pediatric Dermatology
Samuel Weinberg, Neil S. Prose, Leonard Kristal
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