Bma Illustrated Medical Dictionary

sweat glands, sebaceous glands, blood

and lymph vessels, and sensory receptors

for pressure, temperature, and pain.

skin allergyIrritation of the skin follow-

ing contact with a specific substance that

provokes an inappropriate or exagger-

ated reaction from the immune system.

There are 2 main types of allergic skin

reaction. In contact allergic dermatitis,

red, itchy patches develop a few hours

to 2 days after contact with the allergen.

In contact urticaria, red, raised areas

appear a few minutes after skin contact.

In some cases, skin testsare needed, to

identify the allergen, for contact with it to

be minimized. (See also atopic eczema.)

skin biopsyRemoval of a portion of skin

for laboratory analysis in order to diag-

nose a skin disorder.

skin cancerA malignant tumour in the

skin. Basal cell carcinoma, squamous cell

carcinoma, and malignant melanomaare

common forms related to long-term

exposure to sunlight. Bowen’s disease, a

rare disorder that can become cancer-

ous, may also be related to sun exposure.

Less common types include Paget’s dis-

ease of the nippleand mycosis fungoides.

Kaposi’s sarcomais a type usually found

in people with AIDS. Most skin cancers

can be cured if treated early.

skin, disorders of theThe skin is vul-

nerable to various disorders, including

birthmarksand other naevi; infections

that may be viral (such as cold soresand

warts), bacterial (for example, cellulitis),

or fungal (such as tinea, which causes

athlete’s foot); rashes due to vitamin

deficiency or the side effects of drugs;

and tumours, both noncancerous and

cancerous. Acneis common in adoles-

cents and is partly related to the action

of androgen hormones. Inflammation of

the skin occurs in dermatitis, eczema,

and skin allergy. The skin is also vulner-

able to injuries such as burns, cuts, and

bites (see bites, animal; insect bites).

skin flapA surgical technique in which

a section of skinand underlying tissue,

sometimes including muscle, is moved

to cover an area from which skin and tis-

sue have been lost or damaged by injury,

disease, or surgery. Unlike a skin graft, a

skin flap retains its blood supply, either

by remaining attached to the donor site

or through reattachment to blood vessels

at the recipient site by microsurgery, so

skin flaps adhere well even where there

is extensive loss of deep tissue.

skin graftA technique used to repair

areas of lost or damaged skinthat are

too large to heal naturally, that are slow

SKIN ALLERGY SKIN GRAFT

S

SKIN

Scaly upper layer

Sebaceous

gland

Subcutaneous

fat

Epidermis

Dermis

Sweat duct

Hair shaft

Nerve ending

Arrector pili

muscle

Blood vessel

Hair follicle

Hair bulb

Sweat gland

Sweat pore

Venule

Nerve