Hyperpigmentation is the appearance of darker than usual patches on the skin. The opposite would be hypo-pigmentation which is the loss of pigment in the skin.
The skins pigment is determined by the amount of melanin our cells produce. This can be affected by hormonal changes both natural & artificial (pregnancy, HRT, contraceptive pill), medication, fragrances used on the skin and can also develop around a scar or acne lesion).
Exposure to UV rays from the sun or sunbeds, stimulates the production of melanin within our skin cells. This melanin will then rise to the skins surface to protect it from UV damage, so suntanned skin is the result of an increase in melanin production.
Melasma / Chloasma / Mask of Pregnancy: a skin condition presenting as brown patches on the face of adults. This usually occurs in women and occasionally men. Some women overproduce melanin during pregnancy, on the face and occasionally on the abdomen. This usually disappears after the birth and when hormones settle. Often women taking the contraceptive pill or with an IUD experience this. It becomes more prominent with sun exposure and in the summer months.
Post Inflammatory Hyperpigmentation: occurs following trauma to the skin. It commonly occurs after acne spots, legions or aggressive skin treatments or wrong use of products.