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Acanthosis Nigricans

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  1. Classification and Causes
    1. Type 1: Hereditary Benign Acanthosis Nigricans
      1. Idiopathic onset during childhood or Puberty
    2. Type 2: Benign Acanthosis due to Insulin Resistance
      1. Diabetes Mellitus
      2. Androgen Excess (Hyperandrogenism)
        1. Acromegaly (Gigantism)
        2. Cushing's Syndrome
        3. HAIR-AN Syndrome
      3. Hypogonadism
        1. Addison's Disease
        2. Hypothyroidism
    3. Type 3: Pseudo-Acanthosis Nigricans
      1. Obesity resulting in Insulin Resistance
      2. Seen in patients with darker pigmentation
      3. Specific findings
        1. Numerous Skin Tags in axilla and groin
        2. Velvety patch at inner upper thigh areas of chafing
    4. Type 4: Drug-induced Acanthosis Nigricans
      1. Nicotinic Acid (high dose)
      2. Glucocorticoids
      3. Diethylstilbestrol (DES)
      4. Oral Contraceptives (androgenic Progesterone)
      5. Growth Hormone therapy
    5. Type 5: Malignant Acanthosis Nigricans
      1. Causes
        1. Paraneoplastic tumors (Adenocarcinoma)
        2. Lymphoma
      2. Specific findings
        1. Palm and sole hyperkeratosis
        2. Lip vermilion border and Oral Mucosa involved
  2. Signs
    1. Characteristics
      1. Hyperpigmentation patches (dirty-appearing)
      2. Velvety feel and appearance develops over time
    2. Distribution
      1. Nape of neck
      2. Axillae
      3. Groin
      4. Vulva and Perineum
      5. Antecubital fossa
      6. Knuckles
      7. Submammary region
      8. Umbilicus
  3. Evaluation
    1. Consider malignancy
      1. Onset over age 35 years
      2. Non-obese patient
    2. Evaluate for cause of Insulin Resistance
    3. Evaluate for Hyperandrogenism
  4. References
    1. Elmer (2001) Am Fam Physician 63(12):2385
    2. Fitzpatrick (1992) Atlas Dermatology, McGraw, p.732-3
    3. Hacker (1996) Postgrad Med 99(6):177

Acanthosis Nigricans (C0000889)

Definition (MSH)A circumscribed melanosis consisting of a brown-pigmented, velvety verrucosity or fine papillomatosis appearing in the axillae and other body folds. It occurs in association with endocrine disorders, underlying malignancy, administration of certain drugs, or as in inherited disorder.
Definition (CSP)circumscribed melanosis consisting of a brown pigmented, velvety verrucosity or fine papillomatosis appearing in the axillae and other body folds; occurs in association with endocrine disorders, underlying malignancy, administration of certain drugs, or as in inherited disorder.
ConceptsDisease or Syndrome (T047)
ICD9701.2
MSHD000052
EnglishAcanthosis Nigricans, AN - Acanthosis nigricans, Keratosis nigricans
Spanishacantosis nigricans, queratosis nigricans
Parent Conceptsskin disorder (C0037274), Melanosis (C0025209), Dermatitis (C0011603), Disorder of keratinization (C0475811)
SourcesCOSTAR, CSP, CST, DXP, LCH, MSH, MTH, MTHICD9, NCI, NDFRT, OMIM, SCTSPA, SNOMEDCT
Derived from the NIH UMLS (Unified Medical Language System)



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