6.4 - Skin Disorders

acne

inflammation of the sebaceous glands in which the follicle becomes blocked with keratinocytes and sebum and develops into a whitehead (comedo) composed of these and bacteria; oxidation of the sebum turns a whitehead into a blackhead

dermatitis

any inflammation of the skin, typically marked by itching and redness

contact dermatitis

dermatitis caused by exposure to toxic foliage

eczema

itchy, red skin lesions caused by an allergy, usually beginning before age five; may progress to thickened, leathery, darkly pigmented patches of skin

psoriasis

recurring, reddened plaques covered with silvery scale, possibly caused by an autoimmune response

rosacea

red rashlike area, often in the area of the nose and cheeks, marked by fine networks of dilated blood vessels and worsened by hot drinks, alcohol, and spicy food

seborrheic dermatitis

recurring patches of scaly white or yellowish inflammation often on the head, face, chest, and back; called cradle cap in infants

tinea

any fungal infection of the skin, common in moist areas such as the axilla, groin, and foot

skin cancer

most often occurs on the head, neck, and hands, and is most common in fair-skinned people and the elderly

types of skin cancer

basal cell carcinoma, squamous cell carcinoma, and melanoma

lesions

zones of tissue injury

basal cell carcinoma

most common and least deadly type of skin cancer that seldom mestastasizes, arises from cells of the stratum basale, and eventually invades the dermis

squamous cell carcinoma

arises from keratinocytes of the stratum spinosum, tends to mestastisize to the lymph nodes, and typically appears on the scalp, ears, lower lip, or back of the hand

melanoma

extremely aggressive skin cancer that arises from the melanocytes and mestastasizes quickly

depending on the type of cancer and its location, skin cancers are treated by…

surgical excision, radiation therapy, electrodesiccation, or cryosurgery

electrodesiccation

destruction of a lesion by heat

cryosurgery

destruction of a lesion by cold

eschar

burned, dead tissue

burn classifications

first-degree burns, second-degree burns, and third-degree burns

first-degree burns

burns that involve only the epidermis

second-degree burns

burns that involve the epidermis and part of the dermis but leave at least some of the dermis intact

first-degree burns (appearance)

marked by redness, slight edema, and pain

first-degree burns (healing trajectory)

heal in a few days and seldom leave scars

second-degree burns (appearance)

appear red, tan, or white, blistered, and very painful

second-degree burns (healing trajectory)

may take two weeks to several months to heal, and may leave scars

third-degree burns (full-thickness burns)

burns that destroy the epidermis, all of the dermis, and often some deeper tissues, and often require skin grafts

debridement

removal of the eschar in third-degree burns that is essential to infection control