A 36-year-old woman comes to the physician for a rash on her lower abdomen. The rash first appeared 3 months ago and has been slowly expanding in the same area. It is mildly pruritic but otherwise asymptomatic. Treatment with topical emollients has not been beneficial. The patient has a history of depression for which she takes citalopram but is otherwise healthy. Skin examination findings are shown in the image below. Which of the following is the most likely explanation for this patient's symptoms?

Question

A 36-year-old woman comes to the physician for a rash on her lower abdomen.  The rash first appeared 3 months ago and has been slowly expanding in the same area.  It is mildly pruritic but otherwise asymptomatic.  Treatment with topical emollients has not been beneficial.  The patient has a history of depression for which she takes citalopram but is otherwise healthy.  Skin examination findings are shown in the image below.  Which of the following is the most likely explanation for this patient's symptoms?

Quizplus · Accepted Answer

Explanation: This patient has excoriated, lichenified plaques at the beltline; these are typical features of chronic allergic contact dermatitis (ACD). Common ACD triggers include a variety of household and occupational allergens including nickel and other metals, cleaning products, fragrances, and various chemicals involved in rubber, plastic, and leather processing. Identifying a specific allergen is often difficult and may require patch testing. However, the distribution of lesions and a careful history may identify the causative allergen. For example, nickel allergy often presents near sites of frequently-worn jewelry or clothing fasteners, latex allergy often appears near clothing waistbands, and leather allergy typically appears on the feet. Management of chronic ACD requires careful avoidance of allergens. Topical high-potency glucocorticoids (eg, betamethasone, fluocinonide) are useful for treatment of flares in intermittent short courses (<4 weeks). Topical tacrolimus is an alternative for areas where glucocorticoids are contraindicated (eg, the face). (Choice B) Psoriasis is a common inflammatory skin disorder characterized by erythematous, well-defined plaques covered by thick silvery scales. These lesions are typically seen over the scalp, knees, elbows, back, and nail plates. Patients are usually asymptomatic, but some may have mild itching. Psoriasis (Choice C) Tinea corporis is characterized by pink annular plaques with a scaly border and central clearing. This patient has pale lichenified plaques that are more consistent with ACD. Tinea corporis (Choice D) Dyshidrotic dermatitis presents as a vesicular rash on the palms and/or soles that is associated with pruritus, redness, and scaling. The sides of the digits may also be involved, but lesions on the trunk are not typical. Dyshidrotic dermatitis (Choice E) Lichen simplex chronicus ("neurodermatitis") is characterized by thickened excoriated plaques caused by persistent scratching and rubbing. It is associated with anxiety disorders and typically occurs in areas that are easy to reach (eg, arms, legs, neck). Lichen simplex chronicus Educational objective: Chronic allergic contact dermatitis is characterized by pruritic lichenified plaques. The locations correlate with the causative allergen. Common triggers include metals (eg, nickel), cleaning products, and a variety of chemicals used in rubber, plastic, and leather processing. References: Metal allergy--a review on exposures, penetration, genetics, prevalence, and clinical implications. (http://www.ncbi.nlm.nih.gov/pubmed/19831422)

A 36-Year-Old Woman Comes to the Physician for a Rash