Acanthosis Nigricans

From Anvita Health Wiki

Contents 1 Introduction 2 Etiology 3 Pathology 4 Clinical-manifestations 5 Laboratory 6 Radiology 7 Differential-diagnosis 8 Management 9 More General Terms 10 Additional Terms 11 Internet Database 12 References

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 acathosis nigricans

• endocrine disorders associated with insulin resistance

• Type 3: pseudo- acanthosis nigricans

• complication of obesity
• obesity produces insulin resistance
• 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

• 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

• insulin-resistance, type 2 diabetes mellitus

Clinical-manifestations

• general

• generally insidious onset
• hyperpigmentation, an accentuation of normal pigmentation
• thickened skin
• velvety feel & appearance
• distribution

• most commonly in intertriginous regions, especially axillae & groin
• also neck, knuckles, umbilicus, corners of mouth

• type 3

• often on inner & upper thigh as a result of chafing
• often many intertriginous skin tags

• type 5

• hyperkeratosis & hyperpigmentation more pronounced
• hyperkeratosis of palms/ soles
• involvement of oral mucosa & vermilion border of lips
• periorbital papillomatous thickenings

Laboratory

• fasting serum glucose
• hemoglobin A1c

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

• alpha-hydroxy acids
• keratolytic agents
• topical tretinoin ( all-trans retinoic acid)

• treat associated disorders

• diabetes mellitus type 2

• metformin

• weight loss 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

• skin disease (dermatologic disorder, dermatopathy, dermatosis)

Additional Terms

• acanthosis
• paraneoplastic dermatosis

Internet Database

OMIM: 100600
OMIM: 147670

References

1. Color Atlas and Synopsis of Clinical Dermatology, Common and Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 505-507
2. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 171
3. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, American College of Physicians, Philadelphia 1998
4. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 319

acanthosis nigricans