Acanthosis nigricans


Characterized by dark, raised velvet eruption of flexural areas common in diabetics and obese persons.

Acanthosis nigricans is a cutaneous disorder of hyperpigmentation and papillomatosis. 


Generally associated with fibroblast growth factor receptor mutations and genetic or acquired insulin resistance. 


Hypothesized to be due to overproduction of an epidermal growth factor promoter secreted by the associated neoplasm. 

Most often seen in axillae, inguinal region, neck, abdomen and mouth.

Confined initially to flexural surfaces.

Thought to represent insulin resistance.

Some cases are inherited with or without diabetes.

May be related to an internal malignancy or drug toxicity.

Evidence suggests that AN is a heritable condition, strongly influenced by genetics that may have pleiotropic effects on genes related to diabetes and metabolic syndrome. 


More common in African American patients (26.8%) and Latino patients (26.1%) and less common in white patients (6%). 


Patients generally present in childhood or adolescence with hyperpigmented, velvety, papillated plaques in flexural areas, such as the neck, axilla, groin, and fingers. 


Rarely, manifests with involvement of the umbilicus, areolae, and oral cavity. 

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