Atopic dermatitis is a chronic, pruritic, eczematous skin condition that affects approximately 15% to 20% of children in developed countries.2
It is caused by multiple factors, including genetic, neuroendocrine, immune, and environmental factors; infection; and defective epidermal barrier.3
The involved skin is easily infected by bacteria and viruses owing to the disruption of the epidermal barrier function and the innate immune system.
Herpes simplex virus, a member of the double-stranded DNA Herpesviridae family, can infect the epidermis owing to impaired skin protective function such as in AD. Eczema herpeticum is a secondary viral infection usually caused by HSV (either type 1 or type 2) that concomitantly occurs with skin conditions like AD, psoriasis, eczema, irritant contact dermatitis, burns, and seborrheic dermatitis.4
Patients with some features of AD, such as early-onset AD and head and neck AD, or large body surface area involvement, have higher risks of eczema herpeticum.5
Initially, the involved skin might show erythematous changes presenting as small, monomorphic, dome-shaped papulovesicles that rupture to form tiny punched-out ulcers overlying an erythematous base. Patients often present with herpetic vesicles over an extensive mucocutaneous surface, most often the face, neck, and upper trunk. Patients might have accompanying symptoms like fever, malaise, and lymphadenopathy. The virus is presumably spread from a recurrent oral HSV infection or asymptomatic shedding from the oral mucosa.6
Just like other HSV infections, eczema herpeticum can recur. Patients might present with localized HSV infection in previously involved areas. Secondary bacterial infection, mostly due to S aureus
, often occurs because of the inflammatory and extensive nature of the process.7
Therefore, the underlying viral pathogenesis might be misdiagnosed.
Early diagnosis of eczema herpeticum can prevent or minimize complications. The criterion standard for diagnosis of HSV infection is virus culture. In our case, the final virus isolation confirmed our diagnosis. The quality of the swab and culture techniques affect the specificity and sensitivity of virus culture. The microscopic finding of a Tzanck test for multinucleated giant cells can confirm a herpes virus infection and provide rapid diagnosis. Although it is a very easy and quick bedside test, its specificity and sensitivity depend on the operator.5
Direct fluorescence antigen testing is rapid and inexpensive. A fluorescently tagged antibody can detect an HSV antigen and distinguish between HSV-1 and HSV-2 infections.
The clinical manifestation of eczema herpeticum is characteristic; however, it can be confused with impetigo, eczema vaccinatum, and primary varicella infection7
). Eczema herpeticum with secondary staphylococcal infection is a common occurrence that might be misdiagnosed as impetigo, leading to delay in treatment with acyclovir. Misdiagnosis of eczema herpeticum can lead to severe complications, such as herpetic keratitis and death. In an immunocompromised patient, the mortality rate is reported to be as high as 6% to 10% and even 50%.9
Clinicians should be aware that timely diagnosis and treatment of eczema herpeticum are very important to avoid severe complications.
Differential Diagnosis of eczema herpeticum
The main treatment of eczema herpeticum is acyclovir, which is also approved for oral use in patients younger than 18 years of age. For patients with severe disease and immunocompromised patients, systemic antivirus medications and hospitalization are recommended. Owing to the common occurrence of secondary infection with bacteria such as S aureus
, prophylactic antibiotics (eg, cephalexin, clindamycin, doxycycline, or trimethoprim-sulfamethoxazole) should also be administered depending on the geographic susceptibilities.10
Timely and accurate diagnosis of eczema herpeticum at initial presentation is very important. In the case of our patient, eczema herpeticum was initially misdiagnosed as impetigo. Antibiotic treatment is insufficient, and progressive eczema herpeticum might cause blindness and even death. Feye et al11
presented a case of a 38-year-old man who developed a burning vesicular rash and a chronic skin condition over his back and chest. He also complained of a severe burning sensation and watering in both eyes. He received misdirected corticosteroid therapy for “exacerbation of AD.” This resulted in progression of his ocular HSV-1 infection and bilateral keratitis. At this juncture, specific treatment with intravenous and topical ophthalmic acyclovir resulted in regression of eczema herpeticum and keratitis. Feye and colleagues11
emphasized that this condition was a medical emergency and that physicians should recognize such diseases early to avoid ophthalmologic and life-threatening complications.