A. BENIGN ACANTHOSIS NIGRICANS

1. Hereditary benign acanthosis nigricans: This runs in families, but does not usually show any evidence of endocrinological disturbances or internal malignancy.
2. Endocrinal acanthosis nigricans: It is associated with many endocrine problems like acromegaly, addison's disease, Cushing's diseases, insulin resistant diabetes mellitus, hypothyroidism, ovarian hyperthecosis, hepatic cirrhosis,Wilson's disease etc
3. Pseudo acanthosis nigricans: This is a reversible type and usually starts in puberty. It commonly affects dark skinned people and is associated with obesity
4. Drug induced acanthosis nigricans: Nicotinic acid is notorius in causing acanthosis nigricans. Other drugs like stilbostreol, corticosteroids, oral contraceptive pills etc can also cause acanthosis nigricans like lesions.

     B. MALIGNANT ACANTHOSIS NIGRICANS

         Internal malignancies (cancers), especially the adenocarcinomas affecting the stomach, lungs etc  can cause acanthosis nigricans. Sometimes lymphoma may be the culprit.

         Hence it is essential to find out the cause of acanthosis nigricans. Here are a few pointers that may help in differentiating benign from malignant variety of acanthosis nigricans:
          How to Differentiate Between the Benign and the Dangerous Malignant Variety?

Do's:

1. Differentiate between benign and malignant with the help of a dermatologist

2. Reduction of weight 

3. Strict diabetic control

4. Regular aerobic exercises

5. Full investigations including tumor markers, hormonal assay, ultra sound scan, MRI etc

6. Regular medical check up, semi annual

7. Report any sudden changes in morphology

Don'ts

1. Scrub too much, as frequent rubbing will only increase skin thickening and pigmentation

2. Use strong abrasives: tend to irritate  the skin more.

Treatment Guidelines of Acanthosis Nigricans

1. Correction of underlying cause

• Removal of tumor

• Correction of endocrine disorder

• Reduction of weight

• Removal of causative drug

2. Dietary supplimentation with fish oil containing omega 3 fatty acids have been reported to be

   beneficial

3. Cyproheptadine has been found useful in some cases

4. Management of Skin Lesions:

• Toipcal Retin A

• Salicylic acid application alone or in combination with steroids, alternating with emollient applications to minimize irritation.

• In severe unresponsive cases, systemic retinoids may be given a trial.