A common, usually harmless condition in which patches of skin are darker than the surrounding skin. It occurs when special cells in the skin make too much of the pigment called melanin. Hyperpigmentation may appear as freckles, age spots, or larger areas of darkened skin. Hyperpigmentation may be caused by injury or inflammation of the skin, sun damage, abnormal skin growths, hormone changes, pregnancy, or other medical conditions. Certain medicines, including some anticancer drugs, can also cause hyperpigmentation.