Allergic Contact Dermatitis Diagnosis and Treatment

Clinical Features and Diagnosis

The American Academy of Dermatology states that allergic contact dermatitis (ACD) is a delayed-type hypersensitivity reaction that requires patch testing for definitive diagnosis, as it is clinically indistinguishable from other forms of dermatitis 1
The British Journal of Dermatology notes that erythema and vesiculation are hallmark features of ACD, often with visible borders demarcating the area of contact, and pruritus and burning sensations are common accompanying symptoms 2
The American Academy of Dermatology recommends that disease aggravated by topical medications or emollients, patterns reflecting consistent item exposure, and later onset of disease or new significant worsening should raise suspicion for ACD 1
Patch testing should be performed when history or physical exam suggests ACD, when dermatitis has unusual distribution, or when the condition persists despite treatment, with a sensitivity range of 60-80% and specificity of 70-80% 1, 6

The American Academy of Dermatology suggests that complete avoidance of the identified allergen is the most critical step and offers the best chance for resolution, and topical corticosteroids are the cornerstone of acute treatment 1, 4
The American Academy of Dermatology recommends applying mid- to high-potency topical corticosteroids such as triamcinolone 0.1% for localized acute ACD, and escalating to very high-potency agents for persistent dermatitis 1, 4
The British Journal of Dermatology notes that ACD usually carries a worse prognosis than irritant dermatitis unless the allergen is identified and avoided, and complete resolution is expected if the causative agent is identified and completely avoided 2, 5
The American Academy of Otolaryngology-Head and Neck Surgery states that neomycin-containing preparations can cause contact sensitivity in 13-30% of patients with chronic otitis externa, and sensitization occurs over 10-14 days, with subsequent delayed-type hypersensitivity causing erythema, pruritus, inflammation, edema, and persistent otorrhea 3

The American Academy of Dermatology notes that ACD is increasingly recognized in individuals with atopic dermatitis, with prevalence of 6-60% depending on the study, and ACD is at least as common in atopic dermatitis patients as in the general population 1
The American Academy of Dermatology suggests that a small subset of patients develop ACD to topical corticosteroids themselves, posing diagnostic dilemmas, and patch testing to corticosteroid allergens is necessary when this is suspected 1, 4