Acanthosis Nigricans

Acanthosis nigricans is caused by Hyperpigmented, velvety thickening of the skin; most commonly on the neck, in the axillae, and in the groin

The pathogenesis Caused by factors that stimulate epidermal keratinocyte and dermal fibroblast proliferation, such as insulin or an insulin-like growth factor

The Clinical manifestation is Symmetrical, hyperpigmented, velvety plaques, which most commonly appear in the intertriginous areas; skin tags in the

vicinity of the plaques

The differential diagnosis that you can see are Becker nevus; confluent and reticulated papillomatosis of Gougerot and Carteaud; Dowling-Degos disease; seborrheic keratosis; ichthyosis hystrix; linear epidermal nevus; parapsoriasis en plaque; pemphigus vegetans; hemochromatosis; Addison’s disease; pellagra

Therapies for this dermatology disease are correction of underlying disease process; weight reduction in obese patients; tretinoin 0.025% cream; adapalene 0.1% gel; calcipotriene; dietary fish oils; dermabrasion

For more information about this disease, you can read  Hud JA Jr, Cohen JB, Wagner JM, Cruz PD Jr (1992) Prevalence and significance of acanthosis nigricans in an adult obese population. Arch Dermatol 128: 941–944.