What is Hyperpigmentation?

Hyperpigmentation is due to the presence of excessive melanin in the skin cells. It arises from various causes, which include:

• Post-inflammatory hyperpigmentation
• Erythema ab igne – due to prolonged heat exposure, as for instance, over the lap when constantly using a laptop computer, or when a hot water pad or bottle is applied over a long period of time to some part of the body
• Melasma – darkening of skin over the forehead and cheeks, in pregnancy, or when using oral contraceptives
• Becker’s nevus
• Induced by medications such as minocycline, imipramine or amiodarone
• Endocrine disease such as Addison’s disease
• Accumulation of iron in the body, called hemochromatosis or ‘bronze diabetes’, associated with skin darkening in 9 of 10 patients. Due to melanocyte stimulation by metals.
• Tanning due to ultraviolet or sunlight exposure
• Other conditions such as age spots, acanthosis nigricans, and lentigines also cause darkening of the skin in specific places.

Diagnosis

After a careful questioning about possible causes, such as iron overload or medications causing skin to darken, some tests may be indicated, which include:

• Tests of adrenal function
• Tests of thyroid function
• Skin biopsy

Treatment

Non-surgical

• Skin lightening creams should be carefully used, not more than 3 weeks at a time. Always test on an inconspicuous area first. Commonly used topical agents include hydroquinone, kojic acid and retinoids.
• Other non-drug topical agents include licorice, resveratrol, soy and mulberry.
• Use cosmetics to mask a darker area.
• Use sunscreen with an SPF of 30 or more to avoid sunburn or suntan.

Surgery

• Resurfacing or microdermal abrasion.
• Chemicals like tretinoin to peel off the superficial layer of the skin with its contained melanocytes.
• Laser removal of the darkened layer.
• The use of high-intensity light in pulses.
• Fractional photothermolysis.
• Surgery should always be combined with sunscreen use to avoid recurrence of darkening. After resurfacing procedures, drugs like procyanidin, tranexamic acid and Polypodium leucotomos should be taken by mouth to prevent hyperpigmentation from recurring.   

Support or counseling as required.

References

• https://www.nlm.nih.gov/medlineplus/ency/article/003242.htm
• http://www.ncbi.nlm.nih.gov/pubmed/21925372
• http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921758/
• http://www.ncbi.nlm.nih.gov/pubmed/15334278
• http://www.ncbi.nlm.nih.gov/pubmed/19608057
• http://www.ncbi.nlm.nih.gov/pubmed/22640434
• https://www.nlm.nih.gov/medlineplus/skinpigmentationdisorders.html
• http://www.science.gov/topicpages/p/postinflammatory+hyperpigmentation+pih.html