• Credits

  • Section Writer: Dr. Om J Lakhani
  • Section Editor: Dr. Om J Lakhani

• Linked notes

  • 3.0 Clinical features of Insulin resistance

• Q. What is acanthosis nigricans ?

  • It is a common skin change that occurs as a consequence of insulin resistance
  • it is dark, velvety, hyperpigmented plaques on the skin found at intertriginous sites, such as the neck and axillae.
  • 
    • #Real-life-cases- An adolescent with acanthosis nigricans in the back of the neck

• Q. Can acanthosis occur in infants also?

  • Yes

• Q. Enlist the conditions associated with acanthosis?

  • Insulin resistance
  • Obesity
  • Familial acanthosis nigricans
  • Malignancy
  • Genetic syndrome
  • Medications

• Q. How common is type 2 diabetes in patients with acanthosis nigricans?

  • Type 2 Diabetes is twice as common in patients with acanthosis compared to those without it

• Q. Is the serum insulin higher in patients with acanthosis?

  • Yes

• Q. How common is acanthosis in patients with PCOS?

  • 30% have it
  • It is associated even with normal BMI

• Q. Which are the other endocrine conditions associated with acanthosis?

  • Acromegaly
  • Cushing syndrome

• Q. Which are the genetic conditions associated with acanthosis nigricans and insulin resistance?

  • Congenital generalized lipodystrophy- Bernerdinelli Seip syndrome
  • Familial partial lipodystrophy- Koberling- Dunninghan syndrome
  • Alstrom syndrome
  • Robertson – Mendenhall syndrome
  • Leprechaunism
  • Down’s syndrome

• Q. Which are the genetic conditions associated with acanthosis without insulin resistance?

  • Curzon syndrome
  • Cutis gyrata
  • SADDAN- Severe achondroplasia, developmental delay, and acanthosis nigricans
  • Costello syndrome
  • Thantophoric dysplasia

• Q. What is the inheritance and mutation involved in familial acanthosis nigricans?

  • Mutation in FGFR3
  • It has autosomal dominant inheritance

• Q. Which malignancy is associated with Acanthosis nigricans?

  • Abdominal adenocarcinomas especially gastric adenocarcinoma are associated with acanthosis nigricans

• Q. What is the additional cutaneous marker associated with this malignancy?

  • Leser Trelat sign or multiple seborrheic keratosis
  • Tripe palms

• Q. Which drugs are associated with acanthosis nigricans?

  • Glucocorticoids
  • Testosterone
  • Aripiprazole
  • Protease inhibitors

• Q. Which 3 receptors have been proposed in the etiology of acanthosis nigricans?

  • FGFR receptor
  • EGFR receptor
  • IGFR-1 receptor

• Q. Which protein is involved in malignancy-associated acanthosis nigricans ?

  • TGF alpha which acts via EGFR

• Q. What is the clinical description of acanthosis nigricans?

  • Thickened
  • Velvety
  • Hyperpigmented
  • Verrucous
  • Grey-black
  • Plaques of skin

• Q. Which are the common sites?

  • Back of neck
    • 
    • #Real-life-cases- Acanthosis nigricans on the back of the neck
  • Side of neck
    • 
    • #Real-life-cases - Acanthosis nigricans on front and side of the neck. We can also see that this patient has hirsutism
  • Axilla
    • 
    • #Real-life-cases - Acanthosis nigricans in the axilla

• Q. Which are the other sites?

  • Anogenital region
  • Inguinal skin folds
  • Inframammary
  • Abdominal
  • Umbilicus
  • Antecubital fosssa

• Q. What are acrochordons ?

  • Skin tags

• Q. Are acanthosis symmetrical?

  • Yes

• Q. What is Acral acanthosis nigricans?

  • They Hyperpigmented thin plaques are present on the dorsal hand. The lesions are primarily located over the joints.

• Q. Are acanthosis symptomatic?

  • No

• Q. When will you suspect malignancy-associated acanthosis?

  • Older patients
  • Thin patients
  • Rapidly developing acanthosis
  • With Leser Terlet sign or Tripe palms
  • Unexplained weight loss
  • Extensive involvement
  • Associated with pruritis

• Q. What are the typical pathological features of Acanthosis?

  • Hyperkeratosis and Epidermal papillomatosis

• Q. Can histopathology differentiate malignancy-associated acanthosis from other causes?

  • No

• Q. Which other endocrine conditions leads to dark skin pigmentation ?

  • Addison’s disease
  • Pellagra

• **Treatment **

• Q. Does the acanthosis reverse after treatment of the underlying disorder?

  • It is uncertain

• Q. What is a cosmetic treatment for acanthosis?

  • Topic retinoids (tretinoin) or topical vitamin D analogs (Calcipotriene) may be used

• Q. What is IRORAN ?

  • Insulin resistance obesity-related associated acanthosis nigricans

• Q. Does metformin reduce acanthosis?

  • Studies show mixed results
  • However generally it does not reverse

• Q. Many patients excessively scrub the acanthosis, should this be encouraged?

  • No
  • This should be discouraged as it can lead to lichenification which can worsen the hyperpigmentation

• Q. Can laser therapy help?

  • Yes
  • Long pulsed alexandrite laser can help

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