acanthosis nigricans
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Introduction
Diffuse thickening & hyperpigmentation of the skin mostly in intertriginous regions, especially the axillae.
Etiology
(Classification)
- Type 1: benign hereditary acanthosis nigricans
- onset during childhood or puberty
- Type 2: benign acanthosis nigricans
- Type 3: pseudo-acanthosis nigricans
- complication of obesity (most common cause[2])
- obesity produces insulin resistance
- polycystic ovary syndrome
- more commonly seen in patients with darker pigmentation
- Type 4: drug-induced acanthosis nigricans
- nicotinic acid in high doses
- diethylstibesterol in young males
- oral contraceptives
- Type 5: malignant acanthosis nigricans (rare)
- paraneoplastic syndrome
- GI adenocarcinoma (especially gastric cancer)
- urogenital adenocarcinoma
- lymphoma (less commonly)
Pathology
- papillomatosis
- hyperkeratosis
- epidermis with irregular folds
- acanthosis, variable
- increased pigment in basal layer
- epidermal changes may result from hyperinsulinemia
- associated malignancy
- adenocarcinoma, GI or GU, stomach cancer
Clinical manifestations
- general
- generally insidious onset
- hyperpigmentation, an accentuation of normal pigmentation
- thickened skin
- velvety feel & appearance
- velvety brown thickening of the skin of the posterior neck
- distribution
- most commonly in intertriginous regions, especially axillae & groin
- also neck, knuckles, umbilicus, corners of mouth
- distribution may be asymmetric
- type 3
- often on inner & upper thigh as a result of chafing
- often many intertriginous skin tags 3 type 5
- case of type 3 due to obesity (MKSAP20)[2]:
- hyperkeratosis & hyperpigmentation more pronounced
- hyperkeratosis of palms/soles
- involvement of oral mucosa & vermilion border of lips
- periorbital papillomatous thickenings
- weight loss[3]
Laboratory
Radiology
- Chest X-ray
- other studies as indicated to rule out cancer
Differential diagnosis
- Gougerot-Carteaud syndrome
- pityriasis versicolor
- X-linked ichthyosis
- retention hyperkeratosis
- nicotinic acid ingestion
Management
- symptomatic
- treat associated disorders
- diabetes mellitus type 2 & prediabetes
- weight reduction if associated with obesity
- prognosis
- Type 1: accentuated at puberty, may regress with age
- Type 3: may regress with significant weight loss
- Type 4: regress when etiologic agent is discontinued
- Type 5:
- may preced other signs of malignancy by 5 years
- erradication of maligancy may be followed by regression of acanthosis nigricans
More general terms
Additional terms
References
- ↑ Color Atlas and Synopsis of Clinical Dermatology, Common and Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 505-507
- ↑ 2.0 2.1 2.2 Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 171
- ↑ 3.0 3.1 3.2 Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 16, 17, 18. American College of Physicians, Philadelphia 1998, 2006, 2012, 2015, 2018.
Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025 - ↑ Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 319
- ↑ 5.0 5.1 Acanthosis nigricans (image) American Academy of Dermatology https://www.aad.org/public/diseases/color-problems/acanthosis-nigricans
- ↑ 6.0 6.1 DermNet NZ. Acanthosis nigricans (images) http://www.dermnetnz.org/systemic/acanthosis-nigricans.html
- ↑ Rashid RM, Barros BS (image) Hidden Heart Disease: 19 Dermatologic Clues You Should Know. Medscape. June 13, 2017. http://reference.medscape.com/slideshow/hidden-heart-disease-6004452