Skin Pigmentation

Vitiligo

Vitiligo is a common disorder in which symmetrical white or pale macules (flat circumscribed areas of skin or areas of altered skin colour) appear on the skin.

This can affect all races but is more conspicuous in dark-skinned races.

Vitiligo is an autoimmune disease and may occur with other such diseases (e.g. thyroid disease or alopecia areata). It is usually progressive but spontaneous repigmentation may occur.

Albinism

Albinism is the inherited absence of pigmentation in the skin, hair, and eyes, resulting in white hair and pink skin and eyes.

The pink colour is produced by blood in underlying blood vessels, which are normally masked by pigment. Ocular signs are reduced visual acuity, sensitivity to light (photophobia), and involuntary side-to-side eye movements.

Chloasma (melasma)

Chloasma takes the form of ill-defined symmetrical brown patches on the cheeks or elsewhere on the face.

It is a photosensitivity reaction in women who are taking the combined oral contraceptive pills or who are pregnant. It very rarely occurs in men. It can usually be prevented by the use of sunscreens.

Lentigo
(pl. lentigines)

A lentigo is a flat dark brown spot found typically on the skin of elderly people - especially skin exposed to light.

Lentigines have increased numbers of melanocytes in the basal layer of the epidermis. Freckles, in contrast, do not show an increase in these cells.

In lentigo maligna (or Hutchinson's lentigo), which occurs on the cheeks of the elderly, the spot is larger than 2 cm in diameter and has variable pigmentation.

Moles (papilloma)

Moles: A mole is a non-malignant collection of pigmented cells in the skin.

They are relatively rare in infants and young children but increase in numbers during childhood and especially in adolesence, then decline in numbers in old age.

They vary widely in appearance, being flat or raised, smooth or hairy.

Changes in the shape, colour etc., of moles in adult life should be investigated as this may be an early sign of malignant melanoma. (Medical name: pigmented narvus.)

Papilloma: A papilloma is a benign nipple-like growth on the surface of the skin or mucous membrane. Examples include basal-cell papillomas and bladder papillomas.

Naevae

A naevae is a birthmark, that is a clearly defined malformation of the skin that is present at birth.

There are many different types of naevi. Some, including the strawberry naevus and port-wine stain, are composed of small blood vessels.

• The strawberry naevus (or strawberry mark) is a raised red lump usually appearing on the face and growing rapidly in the first month of life. These birthmarks slowly resolve and spontaneously disappear between the ages of five and ten.
• The port-wine stain (or capillary naevus) is described in the following section (below).
• It is not uncommon for a pale or white halo to develop around an ordinary pigmented naevus, especially on the trunk, forming a halo naevus. The pigmented naevus disappears over the course of a few months, this is followed by the disappearnce of the pale area.
• A blue naevus is a small blue-grey papule appearing at birth or later in life, mainly on the extremities. Progression to malignant melanoma is very rare.
• A naevus of Ota (oculodermal melanocytosis) is a blue-grey pigmented area on the cheek, eyelid or forehead with similar pigmentation of the sclera of an eye. It is associated with melanomas of the uvea, orbit, and brain as well as with glaucoma of the affected eye.

Port wine stain (capillary naevus)

A 'Port Wine Stain' (capillary naevus) is a permanent purplish discolouration that may occur anywhere on the body but is usually located on the upper half of the body.

Laser treatment can reduce the discolouration. Occasionally a port-wine stain may be associated with a malformation of blood vessels over the brain, for example in the Sturge-Weber syndrome.