An 18-month-old boy is brought to the emergency department due to fever and facial rash for 2 days. The patient has a history of atopic dermatitis for which his parents occasionally apply over-the-counter steroid cream. He had a flare-up of dry, thickened, itchy skin on his cheeks 4 days ago. Two days ago, the patient developed many overlying, painful bumps that have since increased in number. Vaccinations are up to date. Temperature is 38.5 C (101.3 F). Physical examination shows an uncomfortable-appearing child with numerous painful, clear vesicles over erythematous skin on both cheeks, as well as a few scattered lesions with overlying, dark red crusting. Submandibular lymphadenopathy is present. The rest of the skin appears dry. Which of the following is the most likely etiology of this patient's rash?

Question

An 18-month-old boy is brought to the emergency department due to fever and facial rash for 2 days.  The patient has a history of atopic dermatitis for which his parents occasionally apply over-the-counter steroid cream.  He had a flare-up of dry, thickened, itchy skin on his cheeks 4 days ago.  Two days ago, the patient developed many overlying, painful bumps that have since increased in number.  Vaccinations are up to date.  Temperature is 38.5 C (101.3 F).  Physical examination shows an uncomfortable-appearing child with numerous painful, clear vesicles over erythematous skin on both cheeks, as well as a few scattered lesions with overlying, dark red crusting.  Submandibular lymphadenopathy is present.  The rest of the skin appears dry.  Which of the following is the most likely etiology of this patient's rash?

Quizplus · Accepted Answer

11ec25c8_d646_beb2_bc81_69bab0059a53_MD0003_00 This child with atopic dermatitis has a painful, vesicular rash and fever, findings concerning for eczema herpeticum. This infection is caused by herpes simplex virus (HSV) and is associated with atopic dermatitis, a chronic condition characterized by both skin barrier and immune dysfunction. Eczema herpeticum may represent primary disease (eg, after exposure to a contact with cold sores or asymptomatic viral shedding) or may be caused by reactivated, latent disease. Eczema herpeticum typically begins as painful vesicles on an erythematous base, most commonly involving the face, neck, and trunk. These vesicles are monomorphic (ie, uniform in morphology) and evolve into "punched-out" erosions that become covered with hemorrhagic crusts over the course of 1-2 weeks. Systemic findings, such as fever and lymphadenopathy, are common. "punched-out" erosions Although infection may be localized and mild, as in this case, disseminated and potentially fatal disease, involving the eyes (eg, keratitis) and visceral organs (eg, hepatitis, encephalitis), can occur. Therefore, all patients with eczema herpeticum warrant systemic antiviral (eg, acyclovir) therapy. (Choice B) Molluscum contagiosum is caused by a poxvirus and presents with umbilicated, skin-colored papules (not vesicles) that may be pruritic. Fever and lymphadenopathy are not seen. Molluscum contagiosum (Choices C and D) Most patients with atopic dermatitis are colonized by Staphylococcus aureus, the primary cause of impetigo; Streptococcus pyogenes can less commonly lead to this superficial infection. Presentation includes erythematous papules, pustules, or vesicles that are covered by honey-colored crusts, not hemorrhagic crusts. Moreover, systemic symptoms (eg, fever) would not be expected. honey-colored crusts (Choice E) Trichophyton rubrum is the most frequent cause of tinea corporis (ie, ringworm), and lesions present as pruritic, scaly annular patches, not vesicles. In addition, fever would not be seen. annular patches (Choice F) Primary varicella zoster infection (ie, chickenpox) is characterized by a prodrome (eg, fever, sore throat, fatigue) followed by a diffuse pruritic rash that presents in various stages (eg, macules, papules, vesicles, pustules). This patient's localized and uniformly vesicular rash makes this diagnosis unlikely. diffuse various stages Educational objective: Eczema herpeticum is a potentially fatal cutaneous herpes simplex virus infection associated with atopic dermatitis. Classic presentation includes systemic symptoms (eg, fever, lymphadenopathy) and painful vesicles with "punched-out" erosions and hemorrhagic crusts. References: Eczema herpeticum: Would you know it if you saw it? (http://www.ncbi.nlm.nih.gov/pubmed/26241712) Eczema herpeticum. (http://www.ncbi.nlm.nih.gov/pubmed/22433376)

An 18-Month-Old Boy Is Brought to the Emergency Department Due