Skin – abnormally dark or light
Skin that has turned darker or lighter than normal is usually not a sign of a serious medical condition.
- Normal skin contains cells called melanocytes. These cells produce melanin, the substance that gives skin its colour.
- Skin with too much melanin is called hyper pigmented skin.
- Skin with too little melanin is called hypo pigmented skin.
- Pale skin areas are due to too little melanin or underactive melanocytes. Darker areas of skin (or an area that tans more easily) occur when you have more melanin or overactive melanocytes.
- Bronzing of the skin may sometimes be mistaken for a suntan. This skin discoloration often develops slowly, starting at the elbows, knuckles, and knees and spreading from there. Bronzing may also be seen on the soles of the feet and the palms of the hands. The bronze colour can range from light to dark (in fair-skinned people) with the degree of darkness due to the underlying cause.
Causes of hyperpigmentation include:
- Skin inflammation (post-inflammatory hyperpigmentation)
- Use of certain drugs (such as minocycline and birth control pills)
- Endocrine diseases such as Addison disease
- Hemochromatosis (iron overload)
- Sun exposure
Causes of hypopigmentation include:
- Skin inflammation
- Certain fungal infections (such as tinea versicolor)
- Pityriasis alba
- Certain medicines
- Skin condition called idiopathic guttate hyomelanosis