Main article: Pigment Diseases and conditions
A variety of diseases and abnormal conditions that involve pigmentation arise in humans and animals, either from absence of or loss of pigmentation or pigment cells, or from the excess production of pigment.

Albinism is an inherited disorder characterized by total or partial loss of melanin. Humans and animals that suffer from albinism are called "albinistic" (the term "albino" is also sometimes used, but may be considered offensive when applied to people).
Lamellar ichthyosis, also called "fish scale disease", is an inherited condition in which one symptom is excess production of melanin. The skin is darker than normal, and is characterized by darkened, scaly, dry patches.
Melasma is a condition in which dark brown patches of pigment appear on the face, influenced by hormonal changes. When it occurs during a pregnancy, this condition is called the mask of pregnancy.
Vitiligo is a condition in whch there is a loss of pigment-producing cells called melanocytes in patches of skin.