Acanthosis nigricans

Thickened 'velvety' brown plaques are due to acanthosis nigricans. The same darkened skin is commonly seen in the neck folds. It is caused by insulin resistance and is often a complication of obesity. Weight loss can result in improvement. Acanthosis nigricans may also arise in various endocrine syndromes and rarely, as a paraneoplastic phenomenon. The skin thickening may be lessened with the help of keratolytic creams.