Acanthosis nigricans
- Definition: a condition characterized by velvety, hyperpigmented plaques on the skin that most frequently involve intertriginous sites such as the axillae and neck
- Acanthosis: velvety, thickening
- nigricans: hyperpigmentation
- Etiology
- Endocrinal
- Diabetes mellitus type 2
- PCOS
- Cushing syndrome
- Obesity: pseudoacanthosis nigricans
- Familial causes: autosomal dominant inheritance
- Drug-related causes (e.g., glucocorticoids, oral contraceptives)
- Endocrinal
- Pathogenesis: insulin, IGF, and/or other growth factors (e.g., fibroblast growth factor) → epidermal hyperplasia and fibroblast proliferation
- Clinical findings
- Brown to black, intertriginous and/or nuchal hyperpigmentation that can develop into itching, papillomatous, poorly defined eruption
- Symmetrical thickening of skin
- Localization: axilla, groin, neck
- Brown to black, intertriginous and/or nuchal hyperpigmentation that can develop into itching, papillomatous, poorly defined eruption
- Differential diagnosis: malignant acanthosis nigricans
Tip
Don't mess with skin pigmentation caused by Adrenal insufficiency#Elevated ACTH