Page 171 - fourth year book

SKIN DISEASES

C. Elevated lesions containing fluids

1. Vesicles: are small, clear fluid-filled blisters less than 1 cm in
diameter. Vesicles are characteristic of herpes infections, acute
allergic contact dermatitis, and some autoimmune blistering
disorders (eg , dermatitis herpetiformis).

2. Bullae are clear fluid-filled blisters more than 1cm in diameter.

These may be caused by burns; bites, irritant or allergic contact

dermatitis, and drug reactions.

II. Secondary lesion:

A. Scales: are heaped-up accumulations of horny epithelium seen in

diseases such as psoriasis, seborrheic dermatitis, and fungal
infections. Pityriasis rosea and chronic dermatitis of any type may be
scaly.
B. Crusts (scabs): consist of dried serum, blood, or pus. Crusting can
occur in inflammatory or infectious skin diseases (eg, impetigo).
C. Scars: are areas of fibrosis that replace normal skin after injury. Some

scars become hypertrophic or thickened and raised. Keloids are
hypertrophic scars that extend beyond the original wound margin.

Classification of skin diseases:

I- Bacterial Skin Infection
A. Staphylococci and streptococci
1. Impetigo
2. Boils
3. Cellulitis
4. Abscess

B. Tuberculosis

C. Leprosy

II- Viral infections:
1. Warts
2. Herpes simplex
3. Herpes zoster

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