A 22-year-old man comes to the office due to a facial rash. The patient has a history of cold sores and says he developed a recurrent sore about a week ago after spending hours outside training for a bike race. He applied a new, over-the-counter lip balm to his lips and the affected area for comfort. Three days ago, the sore began to crust over as he expected; however, a new, nonvesicular, pruritic rash developed near the site of the sore and has now spread toward the chin. Examination findings of the rash is shown in the image below: Which of the following is the most likely cause of this patient's current symptoms?

Question

A 22-year-old man comes to the office due to a facial rash.  The patient has a history of cold sores and says he developed a recurrent sore about a week ago after spending hours outside training for a bike race.  He applied a new, over-the-counter lip balm to his lips and the affected area for comfort.  Three days ago, the sore began to crust over as he expected; however, a new, nonvesicular, pruritic rash developed near the site of the sore and has now spread toward the chin.  Examination findings of the rash is shown in the image below:  Which of the following is the most likely cause of this patient's current symptoms?

Quizplus · Accepted Answer

11ec25c8_d287_badd_bc81_d7e9822a786c_MD0003_00 This patient has spreading erythema with overlying yellow-colored crusting consistent with nonbullous impetigo. Impetigo is a contagious bacterial infection of the superficial epidermis usually caused by Staphylococcus aureus or group A Streptococcus. Although impetigo can be caused by primary infection of previously intact skin, this condition more commonly occurs secondarily at the site of prior skin trauma. Risk factors include infection (eg, varicella virus, herpes simplex virus [HSV], scabies), inflammation (eg, eczema, burn), or any open wound (eg, cuts, insect bites). This patient likely had a recurrence of oral HSV infection, thereby creating a disturbance of the skin barrier and an increased risk of bacterial invasion. oral HSV infection Presentation of impetigo includes erythematous papules and pustules that coalesce and rupture, leading to a classic honey-colored adherent crusting. Although localized impetigo can resolve without treatment, topical antibiotics (eg, mupirocin) are typically recommended to decrease risk of transmission to others and autoinoculation to other sites. honey-colored adherent crusting (Choice A) Delayed hypersensitivity reaction (eg, contact dermatitis) often occurs after using a new product (eg, lip balm) and may cause pruritic, erythematous lesions or vesicles with clear fluid. This patient's localized, nonvesicular rash makes hypersensitivity less likely. contact dermatitis (Choice B) Eczema in adults typically causes thickened skin in flexural areas (eg, antecubital fossae) that often appears erythematous and dry when inflamed. Spreading, yellow crusting is suggestive of infection and would not be seen with isolated eczema. (Choice C) Excessive ultraviolent light exposure causes sunburn, often leading to painful erythema, peeling, and blistering. This patient's localized rash with overlying crusting makes this diagnosis unlikely. sunburn (Choice D) Primary oral HSV infection in adults typically causes an exudative pharyngitis with fever and cervical lymphadenopathy. This patient has a bacterial infection that likely followed a recurrence of HSV infection. Educational objective: Impetigo is a superficial skin infection that commonly presents with honey-crusted papules and pustules on the face and extremities. Preexisting trauma to the skin, infection (eg, varicella, herpes simplex, scabies), and inflammation (eg, eczema) are risk factors. References: Impetigo: diagnosis and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/25250996) Impetigo. (http://www.ncbi.nlm.nih.gov/pubmed/28613693)

A 22-Year-Old Man Comes to the Office Due to a Facial