Acanthosis nigricans in Adult
AN can be classified into 8 types:
I. Obesity-associated – Most common; linked to diabetes, insulin resistance, high body mass index (BMI), metabolic syndrome, and polycystic ovarian syndrome (PCOS).
II. Malignancy-associated / cutaneous paraneoplastic syndrome – Most commonly associated with gastric carcinoma, but numerous other malignancies have been reported. Elderly nonobese patients with new AN should have malignancy considered as a cause. Atypical (palmar, perioral, or mucosal) distributions or acute-onset AN may be more associated with malignancy.
III. Drug-induced – Niacin (nicotinic acid) is the most closely associated medication, but AN can also be caused by oral contraceptives, corticosteroids, diethylstilbestrol, heroin, fusidic acid, methyltestosterone, protease inhibitors, and folate.
IV. Syndromic – Type A refers to patients with HAIR-AN (hyperandrogenism, insulin resistance, and acanthosis nigricans) syndrome and acromegaly. Type B is typically seen in women who have uncontrolled diabetes mellitus and autoimmune diseases (systemic lupus erythematosus, scleroderma, Sjögren syndrome, and Hashimoto thyroiditis). This type is associated with the formation of antibodies against insulin receptors.
V. Acral – Affects elbows, knees, and knuckles. Typically seen in healthy sub-Saharan Africans.
VI. Unilateral – Also called nevoid. Usually represents an epidermal nevus in childhood.
VII. Benign – Rare autosomal dominant type developing at birth or during childhood.
VIII. Mixed – Any 2 or more of the above types combined.
Other related endocrinopathies include pituitary hypogonadism, thyroid disease, Addison disease, and acromegaly.
L83 – Acanthosis nigricans
402599005 – Acanthosis nigricans
- Confluent and reticulated papillomatosis of Gougerot-Carteaud (CARP) presents with reticulated, pigmented patches on the trunk.
- Epidermal and Becker nevi are usually not symmetric and often have associated hypertrichosis.
- Hemochromatosis and Addison disease have skin darkening without epidermal thickening.
- Localized plaques of epidermolytic ichthyosis have more corrugated surfaces.
- Pellagra presents with photodistributed dermatitis (Casal's necklace) as well as diarrhea and dementia (the 3 Ds).
- Large plaque parapsoriasis tends to have diffusely distributed, scaly plaques.
- Pemphigus vegetans has verrucous ulcerated plaques.
- Erythema dyschromicum perstans (ashy dermatosis) usually has diffuse hyperpigmentation over the trunk.
- Terra firma-forme dermatosis can be removed by rubbing with isopropyl alcohol.
- Intertriginous granular parakeratosis
- Dowling-Degos syndrome