Patients with atopic dermatitis are at risk for developing the herpes simplex virus (HSV)–related skin complication “eczema herpeticum,” also known as Kaposi’s varicelliform eruption. Eczema herpeticum is characterized by cutaneous pain and vesicular skin lesions, most commonly secondary to infection with HSV-1. The condition may affect individuals with atopic dermatitis or other inflammatory skin disorders. Eczema herpeticum develops when the virus infects large areas of skin, rather than being confined to a small area as in the common cold sore. Eczema herpeticum often appears on the face and neck, although it can appear anywhere on the body. In some cases, the rash may be difficult to distinguish from a patient’s baseline eczema if the latter is poorly controlled. Skin symptoms of eczema herpeticum include clusters of small blisters that are itchy and painful; vesicles that appear red, purple, or black; purulent blisters; or crusting. Classically, the morphology of vesicles or crusted lesions shows a “cluster of grapes” appearance. Eczema herpeticum may present with a high fever, chills, and swollen lymph glands.
Courtesy Dr. Lawrence F. Eichenfield
While a clinical diagnosis based on the history, physical findings, and morphologic appearance of the rash is reasonable, testing may confirm the diagnosis. The most sensitive and specific tests are polymerase chain reaction sequencing for HSV, direct fluorescent antibody stain, and/or viral culture, while Tzanck smear may show characteristic histologic changes. Treatment is with oral antiviral therapy and treatment of the eczema.
Hand, foot, and mouth disease (HFMD) is a common viral illness usually affecting infants and children. The infection often involves the hands, feet, mouth, and sometimes, the genitals and buttocks. The viral exanthem is most commonly caused by the coxsackievirus, of the enterovirus family. Coxsackievirus A16 and enterovirus A71 are the serotypes that are most commonly implicated as the causative agents. HFMD initially presents with a low-grade fever, reduced appetite, and general malaise. About 1-2 days later, the child may develop painful mouth sores with an exanthem that involves the dorsum of the hands, soles of the feet, buttocks, legs, and arms. The exanthem consists of vesicles surrounded by a thin halo of erythema, eventually rupturing and forming superficial ulcers with a gray-yellow base and erythematous rim. The exanthem is itchy, and can be macular, papular, or vesicular. The lesions are nonpruritic, and typically not painful. The diagnosis of HFMD usually is made clinically, although a physician can swab the mouth or get a stool sample for polymerase chain reaction, which will show the virus; treatment is supportive. In children with atopic dermatitis, lesions also can tend to concentrate in areas previously or currently affected by the dermatitis, similar to eczema herpeticum, and the terms eczema coxsackium or atypical HFMD are applicable. In young adults, the disease may present with erythematous papulovesicular lesions on the face, oral mucosa, extensor surfaces of the upper and lower extremities, and palms and soles; confluent, hemorrhagic, and crusted lesions also can be seen on the extremities. Systemic symptoms usually subside in a few days; the skin lesions resolve without scarring in days to weeks.
Dr. Safiyyah Bhatti
Secondary bacterial infection is not uncommon in eczema herpeticum patients, reflecting common Staphylococcus aureus infection in atopic dermatitis patients. Streptococcus also may be seen as a concurrent infection. Treatment of secondary bacterial infection may be considered based on clinic context and culture.
Impetiginized eczema also is in the differential diagnosis of eczema herpeticum. S. aureus and Streptococci are the most important causative organisms. Lesions can manifest as a single red papule or macule that quickly becomes vesicular or eroded. Subsequently, the content dries, forming honey-colored crusts. Impetigo may resolve spontaneously, although in the context of infected eczema both topical anti-inflammatory agents (e.g. topical corticosteroids) along with systemic antibiotics may be a reasonable treatment option. Although our patient had honey-colored crusting, the wound culture showed normal bacterial flora.
Dr. Lawrence F. Eichenfield
Primary varicella infection causes acute fever and rash, with an initial exanthem of disseminated pruritic erythematous macules that progress beyond the papular stage, forming clear, fluid-filled vesicles (like dewdrops on a rose petal). In children, the rash presents on the stomach, back, and face, and then spreads to other parts of the body. Blisters also can arise inside the mouth.
In this patient, perioral HSV PCR 1 was positive, and wound culture showed normal oral flora with no organisms or white blood cells seen. The patient responded well to oral acyclovir, and treatment of his underlying atopic dermatitis with low-potency topical corticosteroids.
Dr. Bhatti is a research fellow in pediatric dermatology at Rady Children’s Hospital and the University of California, San Diego. Dr. Eichenfield is chief of pediatric and adolescent dermatology at Rady Children’s Hospital–San Diego. He is vice chair of the department of dermatology and professor of dermatology and pediatrics at the University of California, San Diego. Neither of the physicians had relevant financial disclosures. Email them at pdnews@mdedge.com.
Sources
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Christine Johnson, MD, Anna Wald, MD, MPH. UpToDate. Epidemiology, clinical manifestations, and diagnosis of herpes simplex virus type 1 infection.
Robert Sidbury, MD, MPH. UpToDate. Atypical exanthems in children.
National Eczema Association. Eczema herpeticum.
Centers for Disease Control and Prevention. Symptoms and diagnosis of hand, foot, and mouth disease (HFMD).