(rooster shown) chicken breed is due to hyperpigmentation, with the bird's feathers, skin, beak, and internal organs all being affected. Hyperpigmentation can be caused by sun damage,
inflammation, or other skin injuries, including those related to
acne vulgaris. People with darker skin tones are more prone to hyperpigmentation, especially with excess sun exposure. Many forms of hyperpigmentation are caused by an excess production of melanin. As the body ages, melanocyte distribution becomes less diffuse and its regulation less controlled by the body. UV light stimulates melanocyte activity, and where concentration of the cells is greater, hyperpigmentation occurs. Another form of hyperpigmentation is post-inflammatory hyperpigmentation. These are dark and discoloured spots that appear on the skin following acne that has healed.
Diseases and conditions Hyperpigmentation is associated with a number of diseases or conditions, including the following: •
Addison's disease and other sources of
adrenal insufficiency, in which hormones that stimulate melanin synthesis, such as
melanocyte-stimulating hormone (MSH), are frequently elevated. •
Cushing's disease or other excessive
adrenocorticotropic hormone (ACTH) production, because MSH production is a byproduct of ACTH synthesis from
proopiomelanocortin (POMC). •
Acanthosis nigricans—hyperpigmentation of
intertriginous areas associated with
insulin resistance. •
Melasma, also known as '
chloasma' or the “mask of pregnancy,” when it occurs in pregnant women.— It is a common skin problem that causes dark discolored patchy hyperpigmentation. It typically occurs on the face and is symmetrical, with matching marks on both sides of the face. The condition is much more common in women than men, though men can get it too. According to the
American Academy of Dermatology, 90 percent of people who develop melasma are women. •
Post-acne marks from post-inflammatory hyperpigmentation. •
Linea nigra—a hyperpigmented line found on the
abdomen during
pregnancy. •
Peutz–Jeghers syndrome—an
autosomal dominant disorder characterized by hyperpigmented
macules on the lips and oral mucosa and gastrointestinal
polyps. • Exposure to certain chemicals such as
salicylic acid,
bleomycin, and
cisplatin. •
Smoker's melanosis •
Coeliac disease •
Cronkhite–Canada syndrome •
Porphyria •
Tinea fungal infections such as
ringworm. •
Haemochromatosis—a common but debilitating genetic disorder characterized by the chronic accumulation of
iron in the body. •
Mercury poisoning—particularly cases of cutaneous exposure resulting from the topical application of mercurial ointments or skin-whitening creams. •
Aromatase deficiency •
Nelson's syndrome •
Graves' disease • Schimke immunoosseous dysplasia (SOID). • As a result of
tinea cruris. • Due to
B12 deficiency. •
Atopic dermatitis as a result of inflammation. Hyperpigmentation can sometimes be induced by
dermatological laser procedures. ==Diagnosis==