Skin discolourations

Types of skin hypopigmentation

There are three main types of skin hypo pigmentation:

1. Vitiligo
2. Post inflammatory hypo pigmentation
3. Albinism

Vitiligo

Is characterized by depigmented areas, usually sharply demarcated and often symmetric, caused by a lack of melanocytes (cells that are responsible for the skin color). Depigmentation may involve one or two spots or may cover most of the skin surface. Hair in vitiliginous areas is usually white. Skin lesions are accentuated under Wood's light.

Vitiligo is an autoimmune condition that causes skin depigmentation. It takes the form of skin white spots with a sharp margin and a milk white color. The normal texture and sensation of the skin are preserved. No scaling occurs.

Postinflammatory hypopigmentation

Follows healing of certain inflammatory disorders (ex. dermatitis), burns, and skin infections. It is related to scars and atrophic skin. Skin pigmentation is reduced, but it may not be milk-white as in vitiligo. Spontaneous repigmentation may sometimes occur.

What is leucoderma?

Leucoderma is just another name for vitiligo: "leuco" means white and "derma" refers to the skin (Greek root).

What is the cause of Vitiligo?

• Vitiligo is the result of the damage or death of the skin’s melanocytes (cells that are responsible for the color of skin). There are different theories about the cause of vitiligo:
• The body’s immune system may destroy melanocytes. Pigment may be destroyed as the body responds to a substance it perceives as foreign (the most accepted theory).
• There is genetic defect that makes the melanocytes susceptible to injury.
• Abnormally functioning nerve cells may produce toxic substances that injure melanocytes
• Melanocytes self-destruction. While pigment is forming, toxic byproducts could be produced injuring and destroying melanocytes.
• Researchers believe that a combination of these theories may provide the best explanation.

Can Vitiligo be associated to other conditions?

Yes, people it can be associated to other autoimmune disorders.

Albinism

Is a rare autosomal recessive inherited disorder in which melanocytes are present but do not form melanin (substance that colors the skin). There are various forms. In tyrosinase-negative albinism, the hair is white, the skin pale, and the eyes pink; nystagmus and errors of refraction are common. They should avoid sunlight, use sunglasses, and during daylight hours use a sunscreen with an SPF of >= 15.

Apart from these three main types of hypopigmentation, a common skin condition that usually causes skin depigmentation is known as Pityriasis.