To understand hypopigmentation, it is helpful to know how skin usually gets its colour. Melanocytes are pigment cells that produce melanin. Melanin is the protein that gives skin, hair, and eyes their pigment or colour. The amount of pigment in the skin usually varies depending on sun exposure and genetics. But pigmentation disorders can also affect the skin’s darkness or lightness. Hypopigmentation is the loss of skin pigment or colour. It may occur all over the body or be localized. In localized hypopigmentation, there may be multiple patches or areas on the skin that appear white. The size and shape of the patches can vary widely.

In people with hypopigmentation, there is either a decrease in melanocytes or melanin itself. A decrease in the amino acid tyrosine can also lead to hypopigmentation. Hypopigmentation can occur in people of all races, but it may be more noticeable in people with darker skin because of the contrast between the natural skin colour and the white patches.