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Pigmentation of the skin normally varies according to racial origin (see Fitzpatrick phototypes) and the amount of sun exposure. Pigmentation disorders are often more troublesome in skin of colour.
The pigment cells or melanocytes are located at the base of the epidermis and produce the protein melanin. Melanin is carried by keratinocytes to the skin surface. The melanocytes of dark skinned people produce more melanin than those of people with light skin. More melanin is produced when the skin is injured, for example following exposure to ultraviolet radiation. The melaninisation process in dark skin is protective against sun damage, but melanisation in white skin (for example after sunburn) is much less protective.
Hormonal effects of oestrogen during pregnancy or due to medication can cause pigmentation of nipples, vulva and abdomen (linea nigra).
Some skin diseases and conditions result in generalised or localised hyperpigmentation (increased skin colour), hypopigmentation (reduced skin colour), or achromia (absent skin colour).
A Wood lamp may be used to assess pigmentation during the examination of the skin, as pigmentary changes are often easier to identify while exposing the affected skin to long wavelength ultraviolet rays (UV-A).
If pigmentation affects an exposed site, daily application of broad-spectrum SPF 50+ sunscreen is important to minimise darkening caused by UVR. Cosmetic camouflage can be used.
The following agents can be used to lighten epidermal melanosis, alone or, more effectively, in combination:
Resurfacing using chemical peels, laser, intense pulsed light (IPL) or dermabrasion may be effective but unfortunately risks further damage to the epidermis and formation of more pigment. Cautious cryotherapy to small areas of postinflammatory pigmentation can be effective but risks causing permanent hypopigmentation.
Cosmetic camouflage using make-up is sometimes the best advice
Benign pigmented lesions may be genetic in origin but long-term sun damage, in combination with the natural ageing of the skin, is often the major contributor. Examples of benign pigmented lesions: Solar lentigines and ephelides. The lesions can vary in size and colour. It is always important to ensure that the lesion is not malignant before removing it.