Skin is the largest organ of the body. It is made up of two layers, the upper 'epidermis' and the lower 'dermis'. The epidermis and the dermis are further divided into other layers. The lower most layer of the epidermis is known as the basal layer and it contains organelles called 'melanosomes'. These melanosomes contain cells called melanocytes which produce a pigment called 'melanin'. The color of skin depends mainly on thiand thes melanin amount of melanin present in the other layers of the epidermis. The thickness of epidermis and vascularity of the epidermis are other factors affecting the color of skin.
What are the causes of hyper pigmentation (increase in skin pigmentation) ?
Hyper pigmentation may either be due to increased melanin deposition in the epidermis or dermis. Epidermal pigmentary disorders respond well to treatment while dermal pigmentation may take a long time to lighten.
Melasma : Seen as brown patches on the face, it is more commonly seen in females after pregnancy. It occurs due to hormonal changes in the body. The pigmentation increases on sun exposure.
Peri-orbital melanosis : Also known as 'dark circles' may be heriditary, due to stress or eye strain
Freckles and Lentigenes : These are tiny black / brown spots on the face and are genetic in origin.
Photomelanosis : This is increased pigmentation due to sun exposure. The pigmentation occurs on exposed skin, commonly on the face, neck and the back.
Sun burn : A condition commonly encountered in fair skinned people due to excessive sun exposure.
Post inflammatory hyper pigmentation :
It may be seen in the following cases
- Seen after healing has occured, like in acne, eczemas, contact dermatitis etc.
- Drug induced pigmentation.
- Pigmentation due to cosmetics especially those containing fragrance.
What is the treatment for hyper pigmented disorders ?
Melasma, Photomelanosis and post inflammatory hyper pigmentation can be treated with topical creams such as hydroxy quinone,Kojic acid, tretinoin, topical steroids ,alpha hydroxy acid creams or azelic acid. If the patient does not improve with these medicines other modalities should be used, which may be ;
- Chemical peeling with tri-chloro acetic acid or glycolic acid.
- Intense pulse light treatment
- Peri-orbital melanosis : Spot glycolic acid peel or electrical stimulation of the skin may be done. One may also try intense pulse light therapy. Iron supplements and anti oxidants help when taken orally.
- Freckles and Lentigens : we have the following modalities
- Spot peel with TCA or glycolic acid
- Fulguration with Radiofrequency
- Nevus can be removed by pigmented laser- Q switched Nd-Yag
- Tattoo may be removed by dermabrasion or laser surgery