External Agents and Their Effects on the Skin

Heat and Cold Injury to the Skin

Type of injury

Clinical presentation

Pathology

Management

Thermal burn ("rule of nines")

10, 20, 30 (see table below)

Coagulation necrosis due to Apoptosis. Non-inflammatory blisters

Severe: Prevent fluid loss and Infection

Minor: Ice, clean, debride, dress, tetanus treatment

Sun burn

Erythma, pain, swelling

Sunburn cells= apoptotic keratinocytes due to DNA damage.

Fluids and Tylenol

Frostbite

Early:redness and pain from vasodition

Late:whiteness and no- pain due to vasoconstriction

Thawing: edema and bleeding blisters

Cellular necrosis due to tissue anoxia

Severe cases result in gangrene

Rapid thawing in warm H2O or air at or below blood temp. Clean, debride, dress, tetanus treatment.

Perniosis (Chilblains)

Red, itchy, painful swellings on fingers/toes after cold exposure. Resolves in warm weather/spring

Intense upper dermal edema, Lymphocytic vasculitis (monocytes near and in vessel wall)

Avoid wet/cold conditions, wear gloves etc.

Associated with lupus erythematosus

Cryoglobulinemia

skin lesions due to cold precipitated proteins (cold exposure provokes symptoms)

Biopsy: acid-Schiff reagent is bright red in superficial dermal vessels

Treat underlying disease (malignancy, connective tissue disease, infections)

Clinical Pathology and Course of Burns

Classification

Depth of Injury

Surface

Sensation

Outcome

First-Degree

Partial epidermis

Dry, scaling

Painful

No scar, heals in 1 week

Second-Degree Superficial

Full thickness epidermis

Blisters, edema

Painful

Redness, heals in 3 weeks

Second-Degree Deep

Epidermis and superficial dermis

Blisters, edema, erythema

Some insensitive areas

Firm thick scar, loss of hair, >1 month healing

Third-Degree

Full thickness skin

Dry, pearly white or grey

No sensation

Total skin loss; Heals by scarring

Ultraviolet Light and the Skin

Infestations and Infections of Skin

Foreign Bodies and Trauma to the Skin