We have already seen the main causes and different types of Acanthosis Nigricans.

As acanthosis nigricans is, at times, a fore-runner of internal cancer, it is important to differentiate between the harmless benign acanthosis nigricans from the malignant variety of acanthosis nigricans, as early diagnosis of cancer could be life saving. It is reported that the appearance of acanthosis nigricans precedes the appearance of internal cancer even before a couple of years!

Malignant Acanthosis Nigricans has to be Differentiated from Benign

Even after treatment of the causative cancer, acanthosis nigricans plays an important role as a followup indicator as well. Usually when the cancer is surgically excised and treated with radiation or chemotherapy, acanthosis nigricans disappears. Any recurrence of acanthosis nigricans later may thus point to recurrence of the cancer.

Curth HO (Archives of Dermatology, Vol 102, 1970) reports a remarkable case of acanthosis nigricans persisting for years even after excising  a leiomyoma of stomach, squamous cell carcinoma of bladder and nephrectomy of one kidney for transitional cell carcinoma in a 84 year old man.Then one lesion of adenocarcinoma was found in his colon and removed. Surprise! His long standing acanthosis nigricans disappeared within a few days without any treatment!

Moral: To achieve cure you must excise the responsible hormone secreting tumor, not just any tumor!

How to Differentiate Benign from Malignant Acanthosis Nigricans?

If any of the following features are present in a patient with acanthosis nigricans, presence of internal cancer may be suspected:

  1. Age of onset: Benign acanthosis nigricans appear soon after birth, childhood or in puberty. Early age of onset should arouse suspicion.
  2. Speed of Progression: If the typical features of acanthosis nigricans appear and progress rapidly, it is indicative of a malignant origin.
  3. Severity of Skin Changes: In malignant acanthosis nigricans, the skin changes are more pronounced compared to the benign types of acanthosis nigricans. The dark color (pigmentation) is present beyond the area of thickening in the malignant acanthosis nigricans.
  4. Distribution of Skin Lesions: In malignant acanthosis nigricans, there is extensive involvement of the skin, almost all folds and palms and soles and face are involved.
  5. Mucous membrane involvement: In contrast to the benign acanthosis nigricans, mucous membrane involvement is prominent in about 50% of malignant type of acanthosis nigricans.
  6. Skin Tags: Sudden appearance of skin tags in a case of acanthosis nigricans is indicative of serious underlying illness.
  7. Symptoms: Most benign acanthosis nigricans are asymptomatic. Usually there is irritation and itching in the skin lesions of malignant acanthosis. 

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Published by Dr Hanish Babu, MD on 29th May, 2018

The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or the website will not be responsible for any consequences. The images provided are for illustration purpose only and are copyrighted.

Copyright 2018 © Dr Hanish Babu, MD

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