Symptoms & signs
: erythema and intracellular
edema in epidermal layers (spongiosis
) => blistering and severe
itching. If chronic => dermatofibrosis, with pigment
changes and areas of hair loss, persisting for many years.
: small pieces of gauze or filter paper impregnated with sussmall
amounts of specific pected allergens are applied to the skin of your back,
and then covered with tape, for fixed time periods. After 48 hours, the
doctor removes the tape and examines the underlying skin for signs of an
allergic reaction; swelling or redness constitutes a positive reaction.
A second reading is done after 3-7 days.
AL test : a type of patch test in which the materials being tested
are applied to cellulose disks arrayed on polyethylene-coated aluminum
paper, which is affixed to the skin for several days
Finn chamber test : a type of patch test in which the materials
being tested are held in shallow aluminum cups (Finn chambers) that are
taped against the skin, usually for several days.
thin layer rapid use epicutaneous (TRUE) test : a ready-to-use method
for patch testing, consisting of a desiccated mixture of allergen and hydrophilic
gel printed on a mylar backing; after application the gel absorbs water
from the skin and releases allergen.
complications : excited skin syndrome /
angry back : nonspecific cutaneous hyperirritability of the back, sometimes
occurring when multiple positive reactions are elicited in patch tests
screening a battery of substances
Therapy : fluorurated glucocorticoids,
MnSO4 solution to reduce the itching, nonirritating moisturizer
to help restore the normal texture of the skin (ointment or cream that
contains few potential allergens : petroleum jelly, Vanicream, Cetaphil,
Eucerin, oatmeal baths (Aveeno))
Prognosis : clear up within 1-2 weeks,
as long as you stop exposing your skin
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