Pigment Health Dictionary

A rare disease in which DNA repair mechanisms fail, rendering the skin especially vulnerable to damage from ultraviolet light (see ULTRAVIOLET RAYS (UVR)). Extreme photosensitivity begins in infancy; later, marked freckling occurs and premature CARCINOGENESIS in the skin usually leads to early death. There may also be neurological complications.... xeroderma pigmentosum

Coloration of the skin, hair, and iris of the eyes by melanin. The more melanin present, the darker the coloration. Blood pigments can also colour skin (such as in a bruise).

There are many abnormalities of pigmentation.

Patches of pale skin occur in psoriasis, pityriasis alba, pityriasis versicolor, and vitiligo.

Albinism is caused by generalized melanin deficiency.

Phenylketonuria results in a reduced melanin level, making sufferers pale-skinned and fair-haired.

Areas of dark skin may be caused by disorders such as eczema or psoriasis, pityriasis versicolor, chloasma, or by some perfumes and cosmetics containing chemicals that cause photosensitivity.

Permanent areas of deep pigmentation, such as freckles and moles (see naevus), are usually due to an abnormality of melanocytes.

Acanthosis nigricans is characterized by dark patches of velvet-like, thickened skin.

Blood pigments may lead to abnormal colouring.

Excess of the bile pigment bilirubin in jaundice turns the skin yellow, and haemochromatosis turns the skin bronze.... pigmentation

An inherited condition in which there is degeneration of the rods and cones of the retina at the back of both eyes.

The 1st symptoms appear during or after adolescence and include night blindness.

Tests show a ring-shaped area of blindness which, over some years, extends to destroy an increasing area of the visual field, though central vision is retained, often for many years.

Opthalmoscopy reveals several masses of black pigment corresponding to the areas of visual loss.

Affected individuals and their parents should have genetic counselling.... retinitis pigmentosa

coloured compounds – breakdown products of the blood pigment *haemoglobin – that are excreted in *bile. The two most important bile pigments are bilirubin, which is orange or yellow, and its oxidized form biliverdin, which is green. Mixed with the intestinal contents, they give the brown colour to the faeces (see urobilinogen).... bile pigments

an inflammatory disease of the retinal pigment epithelium (RPE; see retina). Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) is characterized by the presence of multiple cream-coloured irregular lesions scattered in the posterior segment of the eye. The disease occurs in young adults and usually affects both eyes. Visual acuity usually recovers with time.... pigment epitheliopathy