Common pigmentation disorders

By Dr Rakesh Newaj, Specialist Dermatologist

Arwyp Medical Centre, Kempton

The colour of the skin defines our race and is a result of our geographic origin and ancestry. This colour is produced by the interaction of four pigments: haemoglobin, oxyhaemoglobin, carotene and more importantly, melanin. The production of melanin is tightly regulated by several genes and the interaction with UV rays. There are several reasons for skin de-pigmentation, including hormonal, genetic, infectious, inflammatory, excessive UV exposure as well as dietary causes. Some of these disorders include:

Albinism is a genetic disease where there is an absence of melanin in the skin, hair and eyes. There are several different variants, with nine of them inherited as autosomal recessive and one of them as dominant. Thus it is more seen in communities that intermarry. People with Albinism have photophobia, poor vision, squinting and nystagmus. Skin cancers, particularly actinic keratosis, squamous cell carcinomas and occasionally melanomas are common. As far as management is concerned, there is no specific therapy, apart from early and rigid photo-protection, regular surveillance of the skin for malignant changes and ophthalmic care.

Vitiligo is a disease that occurs as a result of acquired destruction of the melanocytes in the skin. This results in white patches which may affect the whole skin surface. It is much more stressful for darker people as the contrast is much more visible. The exact cause of the disease is unknown however several theories link it to autoimmune origin. If caught early, the disease can usually be stopped from progressing and most of the de-pigmentation can be reversed. However, treatment is slow and patients need to be properly counseled.

Piebaldism presents at birth with white patches that look very similar to vitiligo. It is inherited in some cases. The unusual distribution is very characteristic and involves the middle of the upper arms down to the wrists, mid-thighs to the mid-calves or the shins. There is usually a white forelock of hair, which is known as polioses. This disease does not progress and there is no treatment.

Post-inflammatory hypo-pigmentation is more commonly seen in darker people. It occurs as a result of temporary failure of pigmentation following an inflammatory disease. Common causes are eczema, pityriasis alba, pityriasis versicolor, psoriasis and impetico in children.

Melasma is a very common disease affecting mainly women. It presents wit patchy increased pigmentation of the face, often precipitated by pregnancy or oral contraceptives and exacerbated by sunlight. The mainstay of treatment is good sun-protection for the rest of their lives and potent bleaching creams. Patients tend to benefit from cosmetic procedures like skin peels and fractional lasers. However, relapse is common and patients should be properly counseled about it.

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