CHAPTER 16 CONTACT DERMATITIS 267
Drug reaction
Parasite hypersensitivity or infestation
Insect bites
Bacterial folliculitis
Malasseziadermatitis
Dermatophytosis
Demodicosis
Cutaneous lupus erythematosus
Seborrheic dermatitis
Solar dermatitis
Thermal injuries
Trauma from rough surfaces
DIAGNOSTICS
Closed-patch testing:
Discontinue corticosteroids and NSAIDs 3–6 weeks before testing
Use materials directly from the environment or a standard patch test kit for
humans applied to the skin under a bandage for 48 hours
After 48 hours, patch test allergens are removed from the skin. The test area
should then remain protected and examined over the next 3–5 days for changes.
Best diagnostic test: eliminate contact irritant or antigen (minimum 7–14 days); fol-
low with provocative exposure (dechallenge/challenge testing).
Exudate preps to examine for bacterial or yeast infection.
Bacterial cultures to define secondary bacterial folliculitis if indicated.
Clipping a patch of hair in a nonaffected region should result in further development
of a local reaction by facilitating contact with the antigen.
Skin biopsy:
Submission of samples from early lesions preferable to chronic lesions
Biopsy samples from areas under patch test sites particularly useful
Mainly nonspecific superficial perivascular dermatitis with intraepidermal vesic-
ulation and spongiosis in both ICD and ACD
ICD: epidermal degeneration, polymorphonuclear cell infiltrate with leukocyte
exocytosis
ACD: lymphocytic spongiotic or eosinophilic and lymphocytic spongiotic infil-
trate progressing to vesiculation; intraepidermal neutrophilic or eosinophilic
pustules.
THERAPEUTICS
Eliminate or avoid offending substance(s).
Bathe with hypoallergenic shampoos to remove antigen from the skin.
Create mechanical barriers, if possible – socks, shirts, restriction from environment.