A 26-year-old man comes to the office due to upper and lower limb skin lesions that have been present for the past week. The lesions started as small, red papules that gradually enlarged but are not painful or pruritic. The patient had similar lesions several months ago and was told that the antibiotic prescribed for a dental infection could be the cause. The lesions spontaneously resolved in about 2 weeks. Prior to the current episode, he was not taking any medications. The patient occasionally drinks alcohol and does not use tobacco or illicit drugs. Temperature is 36.6 C (98 F), blood pressure is 126/78 mm Hg, and pulse is 76/min. Skin examination shows several lesions (shown below) scattered over the extremities with relative sparing of the trunk. There is no mucous membrane involvement. Which of the following is most likely related to this patient's skin condition?

Question

A 26-year-old man comes to the office due to upper and lower limb skin lesions that have been present for the past week.  The lesions started as small, red papules that gradually enlarged but are not painful or pruritic.  The patient had similar lesions several months ago and was told that the antibiotic prescribed for a dental infection could be the cause.  The lesions spontaneously resolved in about 2 weeks.  Prior to the current episode, he was not taking any medications.  The patient occasionally drinks alcohol and does not use tobacco or illicit drugs.  Temperature is 36.6 C (98 F), blood pressure is 126/78 mm Hg, and pulse is 76/min.  Skin examination shows several lesions (shown below) scattered over the extremities with relative sparing of the trunk.  There is no mucous membrane involvement.  Which of the following is most likely related to this patient's skin condition?

Quizplus · Accepted Answer

This patient's rash is consistent with erythema multiforme (EM), an acute inflammatory disorder that can involve the skin of the extremities, face, trunk, and neck. Severe cases (EM major) can also affect oral mucosa. The appearance can vary, but patients typically develop erythematous papules that evolve into target lesions with a dusky central area, a red inflammatory zone surrounded by a pale ring, and an erythematous halo at the periphery. EM represents a cell-mediated immune process that is typically associated with certain infections (eg, herpes simplex virus [HSV], Mycoplasma) and may be an immune response against antigens deposited in the skin. EM can also be associated with certain medications (eg, sulfonamides), malignancies, and collagen vascular diseases. The diagnosis is usually based on clinical findings, although biopsy can be helpful. EM is self-limited, and symptoms may be alleviated with antihistamines and topical glucocorticoids. Despite the association with HSV (which causes painful recurrent genital vesicles or ulcers), antiviral therapy does not shorten the course. (Choice A) Tinea corporis is transmitted by contact with an affected person or via fomites. It is characterized by pruritic plaques with a scaly border and central clearing. The dusky center and acute, relapsing course of this patient's lesions are not consistent with tinea corporis. Tinea corporis (Choice B) IgE-mediated food allergies present with rapid onset of urticaria, usually within minutes of exposure. Urticaria are characterized by pruritic, raised, erythematous plaques that arise suddenly and resolve over several hours. Urticaria (Choice C) Sporotrichosis is a fungal infection acquired by direct traumatic inoculation of the skin. It is characterized by ulcerating pustular nodules at the site of inoculation and associated lymphatic channels. Sporotrichosis (Choice D) The characteristic skin lesion in Lyme disease (transmitted by the Ixodes tick) is erythema migrans, a slowly expanding erythematous macule or patch with central clearing. Untreated patients may develop multiple lesions. However, compared with EM, the lesions are flatter and are located primarily on the trunk rather than the extremities. erythema migrans Educational objective: Erythema multiforme is an acute inflammatory disorder characterized by erythematous, round papules that evolve into target lesions, although the appearance can vary. It is associated with certain infections (especially herpes simplex) as well as medications, malignancies, and connective tissue diseases. References: Erythema multiforme. (http://www.ncbi.nlm.nih.gov/pubmed/25344713)

A 26-Year-Old Man Comes to the Office Due to Upper