Page 168 - fourth year book

SKIN DISEASES

Diagnosis of skin disease.

It begins by taking history, physical examination, and laboratory
investigations when needed as .

A variety of skin tests may be performed to diagnose skin allergies,
bacterial or fungal skin infections, other problems affecting the skin
and to differentiate between malignant (cancerous) cells and benign
(noncancerous) growths.

The most common skin tests include:

 Patch testing: Fig. Patch Test Patch tests are used to help diagnose
skin allergies. Identified allergens (substances that a person may be
allergic to) are applied to the skin on the back with medicated
adhesive patches and left for a period of time. The skin is then
examined for any reaction.

 Skin biopsy : Skin biopsies are performed to diagnose skin
cancer or benign skin disorders. During a skin biopsy, skin is
removed (after a local anesthetic is applied) and is taken to a
laboratory for analysis. Stitches may be used to close the wound.

 Culture: A culture is a test that is done to identify the
microorganism (bacteria, fungus, or virus) that is causing an
infection. Skin (surface scrapings, biopsies, contents of pus bumps

and blisters), hair, or nails may be cultured to detect bacteria,
fungi, or viruses.

Technique of Ordinary Patch Test

The reaction may be detected after 30 minutes as in contact
urticaria. These are usually read at 48-72 hrs , after removal of adhesive
tape wait for 15 min then check it and again up to 1 week.

If pruritus, pain or irritation occurs, patch testing should be
removed and mild steroid may be applied to the area.

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