A 49-year-old man comes to the office due to a rash. For the last year, the patient has had a red, itchy patch of skin on his leg. Clear, yellow fluid occasionally seeps from it. He has tried changing soaps and cleaning products and has applied various emollients without a change in symptoms. Medical history is unremarkable; the patient lives alone with 2 dogs and is not sexually active. Vital signs are normal. Examination findings are shown in the exhibit. Which of the following is the most likely diagnosis of this patient's rash?

Question

A 49-year-old man comes to the office due to a rash.  For the last year, the patient has had a red, itchy patch of skin on his leg.  Clear, yellow fluid occasionally seeps from it.  He has tried changing soaps and cleaning products and has applied various emollients without a change in symptoms.  Medical history is unremarkable; the patient lives alone with 2 dogs and is not sexually active.  Vital signs are normal.  Examination findings are shown in the exhibit.  Which of the following is the most likely diagnosis of this patient's rash?

Quizplus · Accepted Answer

This patient has a pruritic, scaly, fissured plaque with intermittent exudate consistent with nummular eczema (NE). NE is an idiopathic inflammatory disorder that most commonly affects the skin of the extremities. The incidence is highest in middle-aged and older individuals. The cause is uncertain, but frequent occurrence in the setting of chronically dry skin suggests decreased production of skin lipids. The name refers to the characteristic round lesions that would fit under a large coin (nummum is Latin for "coin"). The diagnosis of NE is based primarily on clinical findings. Biopsy can be considered in atypical cases, but most plaques improve with empiric therapy, eliminating the need for extensive diagnostic testing. First-line treatment includes topical glucocorticoids (eg, betamethasone dipropionate). Patients are also counseled on measures to reduce xerosis (eg, emollients, minimizing use of harsh soaps). (Choice A) Allergic contact dermatitis can cause scaly plaques similar to those of NE, but it usually occurs on exposed skin (eg, hands) or areas with specific allergen exposure (eg, dorsum of feet in allergy to leather dyes, neck in allergy to nickel jewelry). (Choice B) Ecthyma is a streptococcal skin infection related to impetigo. It can form round, erythematous plaques but presents acutely and is often associated with pustules and small ulcers. Ecthyma is different from ecthyma gangrenosum, which is seen with pseudomonal bacteremia and presents as painless red macules quickly evolving into vesicles and necrotic ulcers. ulcers (Choice C) 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. excoriated plaques (Choice E) Psoriasis typically presents with thickened plaques with a prominent white or silver scale. It occurs predominantly in areas exposed to pressure or friction (eg, knees, elbows). white or silver scale (Choice F) Tinea corporis presents with round, pruritic plaques that typically form an annular pattern with peripheral scaling and central clearing. central clearing Educational objective: Nummular eczema is an idiopathic inflammatory disorder that presents with round, pruritic, scaly plaques, most commonly on the extremities. It is often associated with dry skin. The diagnosis is based primarily on clinical findings. Treatment includes topical glucocorticoids, emollients, and avoidance of harsh soaps. References: Annular lesions: diagnosis and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/30216021)

A 49-Year-Old Man Comes to the Office Due to a Rash