Skin Diseases with an Immune Component, Part I: Allergic and Hypersensitivity-Related Conditions

Skin Diseases with an Immune Component, Part I: Allergic and Hypersensitivity-Related Conditions

Editor-in-Chief: Nikki A. Levin, MD, PhD
Editor-in-Chief: Cathleen K. Case, MS, ANP-BC, DCNP
Medical Writer for original manuscript: Nancy J. Nordenson, MT (ASCP), MFA
Medical Writer for updates to manuscript: Joshua F. Kilbridge

Contact Dermatitis (Irritant and Allergic)

Contact dermatitis presents as an itchy erythematous or vesicular rash when acute, and as dry, lichenified, fissured skin when chronic.⁷ Irritant contact dermatitis is a nonimmunologic condition caused by exposure to an irritant, such as a caustic agent.⁷ In contrast, allergic contact dermatitis is a T-cell–mediated (ie, type IV) hypersensitivity reaction caused by sensitization to an allergen.⁷

Allergic and irritant contact dermatitis often cannot be differentiated by clinical presentation alone.⁷Patch testing using one or more screening series should be performed to identify a cause.⁷ The relevance of patch test results should be determined within the context of the patient’s current and past exposures.⁷

Management includes avoidance of and/or protection from (eg, gloves for hand dermatitis) the triggering irritant or allergen.⁷ Topical corticosteroids are first-line treatment; second-line treatments include psoralen plus ultraviolet A light, azathioprine, and cyclosporine.⁷

Case example

A 24-year-old hairdresser presents with a 6-month history of itchy red skin on her hands and wrists. She admits to having direct exposure to multiple chemicals, including hair dye, relaxers, and cleaning products. She has been using triamcinolone 0.1% cream on the rash without much improvement.

On examination, the patient has erythematous, fissured, oozing plaques on her dorsal hands and wrists and some small vesicles between her fingers. The palms are erythematous and scaly. A potassium hydroxide preparation of scale from her hands is negative for fungal hyphae.

Given that the differential diagnosis of the patient’s eruption includes allergic contact dermatitis (as well as atopic dermatitis, psoriasis, tinea manuum, and irritant contact dermatitis), she is scheduled for evaluation by patch testing. Nursing staff apply the patches of a standard series of allergens to the patient’s back, in addition to supplementary allergens associated with hairdressing. The patches on the back are secured with surgical tape and carefully marked with surgical marker for future reference. The patient returns at 48 hours to have the patches removed and the early reading performed. She returns at 96 hours for a late reading of the patch tests. She is found to be markedly allergic to glutaraldehyde, a sterilizing agent, as well as to Group B corticosteroids, which include triamcinolone.

Based on these results, the patient is advised to wear protective gloves when handling chemicals at work and to discontinue triamcinolone. She is prescribed twice-daily hand soaks in a coal tar solution, application of a non–cross-reacting corticosteroid ointment twice daily, and oral antibiotics for presumed secondary infection. She is asked to use petrolatum on her skin after hand washing.

This case demonstrates that workers in certain occupations, such as hair dressing and cosmetology, are at high risk for allergic contact dermatitis due to frequent exposure to chemicals. Patients with dermatitis of any etiology may then become allergic to topical corticosteroids, as happened to this patient. Patch testing is the gold standard evaluation for determining specific allergens causing dermatitis. Counseling patients by providing them with detailed information regarding products to avoid is essential to prevent recurrence or persistence of contact dermatitis.