PracticalDermatology

A  21-year-old woman presents with a 10-day history of pruritic, erythematous macules and patches surmounted by yellow seropurulent crusts in a perioral distribution. Pink papules appeared initially and then rapidly evolved into pustules. The eruption began within just a few days of beginning a new summer job at a daycare center. The patient states she enjoys hiking and spends much of her free time outdoors. Medical history is pertinent for atopic dermatitis. The patient denies concomitant cough or fever, and any recent travel outside the US. 

 Based on the patient’s history and clinical presentation, what is the most appropriate intervention (choose one)?

A. Perform a potassium hydroxide (KOH) scraping to confirm the clinical impression of tinea faceii. Initiate a 2-week course of a topical azole or allylamine antifungal. Inform patient in order to reduce the risk of re-infection, household members and pets should be examined and treated if they are found to be the source of infection. 

B. Based on the patient’s history and clinical presentation, this is most likely phytodermatitis, or plant dermatitis. Reassure patient this will most likely resolve spontaneously, provided repeat contact with the responsible plant is avoided. In order to expedite improvement, prescribe a mid-potency topical corticosteroid. Inform patient this is not contagious, and she can continue working. 

C. The eruption most likely represents impetigo. Instruct the patient to gently cleanse the areas daily with antibacterial soap and prescribe mupirocin ointment to apply to the nares 1-2 x daily for 7 days. An oral antibiotic such as cephalexin may be prescribed. Inform the patient that impetigo is contagious and that she should avoid returning to work until a few days after starting antibiotics. 

D. The patient most likely is experiencing primary herpes simplex infection, and as such, prescribe oral acyclovir or valacyclovir.  Educate the patient regarding the recurrent nature of this infection and that subsequent episodes are very likely.

Answer: C. 

The patient is experiencing an impetigo infection. The lesions begin as papules, which quickly evolve into flaccid vesicles or pustules and, once ruptured, a characteristic yellow or “honey colored” crust forms. Children aged 2-5 years are most commonly affected, but impetigo may also be seen in older children and adults as well. The face and extremities are the most common sites of infection. The diagnosis is typically made clinically, but if doubt exists, a bacterial culture may be obtained.

Staphylococcus aureus most commonly causes impetigo, although Beta-hemolytic streptococci may be the responsible pathogen in a minority of cases… A warm and humid climate favor infection. Patients who have impaired skin barrier function are at higher risk of developing bacterial infections such as impetigo. Any skin trauma, including but not limited to wounds, abrasions, burns, dermatitis, scabies, and pre-existing dermatitis, can all be factors that predispose patients to impetigo. Postinfectious sequelae are rare, but glomerulonephritis and rheumatic fever may occur after streptococcal skin infection.

Treatment of impetigo includes topical therapy such as mupirocin or retapamulin if localized, or systemic antibiotics such as cephalexin or dicloxacillin in more extensive or “deeper” (ecthyma) cases.