Melasma. This is a familiar and somewhat feared term, related to brown to grey-brown patches of pigmentation on the face. It usually shows up on the cheeks, bridge of the nose, forehead, chin and above the upper lip, as well as the forearms and neck. Melasma is usually triggered by hormonal changes associated with pregnancy (which is why the condition is also known as a pregnancy mask), use of birth control pills, hormone replacement or thyroid dysfunction.
Lentigo, commonly called age spots, sun spots or liver spots, is another form of hyperpigmentation. Lentigenes, as these spots are referred to, arise from intrinsic ageing of skin, as well as excessive sunlight.
Hyperpigmentation may also occur at a specific spot, following a minor injury or even a pimple.