Eczema Herpeticum

A 6-month-old boy with a history of atopic dermatitis presented with a 3-day history of a new rash. The papulovesicles had first appeared on his left antecubital fossa and then had spread to involve his left shoulder, chest, forearm, and ultimately his left periorbital region.

He was taking no medications, with only petroleum jelly and moisturizing creams being applied daily for his atopic dermatitis. Except for occasional low-grade fevers for the past few days and a slight increase in irritability, he had had no other apparent symptoms and had continued to eat without difficulty.

Physical examination showed an otherwise healthy, afebrile but fussy infant who was scratching at the rash. Results of a Tzanck smear of the base of a vesicle revealed multinucleated giant cells, leading to the diagnosis of eczema herpeticum. Viral cultures later returned positive for herpes simplex. He was admitted and treated with intravenous acyclovir and oral cephalexin for bacterial superinfection. He responded well and, after transition to oral acyclovir, was discharged home 3 days later to complete 10-day courses of acyclovir and cephalexin.

Eczema herpeticum is a disseminated, vesicular, viral infection usually caused by the herpes simplex virus. It is most often a complication of atopic dermatitis.¹ While its severity can vary, eczema herpeticum in young infants is a medical emergency. Early diagnosis and treatment may be life saving²; before the availability of antiviral medications, mortality reached 10%. Fatality results from viremia with infection of internal organs or, more commonly, from bacterial superinfection and bacteremia with organisms such as Staphylococcus aureus, Streptococcus species, and Pseudomonas species.³

Eczema herpeticum typically presents in areas of active or recently healed atopic dermatitis. Clusters of vesicles and umbilicated pustules appear, gradually forming punched-out erosions with hemorrhagic crusts and associated erythema. High fever and adenopathy may be seen in the initial 2 to 3 days after the onset of the eruption.² New crops of vesicles can appear for several days, and normal-appearing skin ultimately may become involved. Eye involvement, herpes keratitis, is considered an ophthalmic emergency.⁴

Diagnostic tests for eczema herpeticum include Giemsa-stained Tzanck smears of cells scraped from a vesicle base, direct fluorescent antibody staining of vesicular fluid, viral polymerase chain reaction, and viral cultures.⁵ Bedside Tzanck smear (showing multinucleated giant cells) and antibody staining can provide rapid results, whereas confirmation by viral culture generally takes more than 48 hours.¹ Viral polymerase chain reaction is highly specific and more sensitive than culture but often is more costly than other diagnostic studies.⁵

Once eczema herpeticum is suspected, immediate treatment with acyclovir should be initiated. Oral antivirals are adequate for milder cases, but intravenous acyclovir should be given if the disease is severely disseminated.³ Cutaneous pain and pruritus may be treated symptomatically with analgesics,⁵ cool wet compresses,² and a soothing ointment such as petroleum jelly. Ophthalmology consult is necessary if the skin near the eyes is affected.⁵ If topical corticosteroids or tacrolimus are being used to manage atopic dermatitis, they may be continued as long as the child is on acyclovir.

Patients with atopic dermatitis often have secondary impetiginization with S aureus or may be heavily colonized with S aureus at baseline. Eczema herpeticum with bacterial superinfection can have a slower resolution, progress to sepsis, or even lead to death.⁵ Therefore, bacterial culture with antibiotic sensitivities should be performed, and appropriate systemic antibiotics prescribed.

Of the estimated 17% of children affected by atopic dermatitis, less than 3% develop eczema herpeticum.⁶ This incidence is reportedly increasing, however.⁷ Risk factors for developing eczema herpeticum include an early age of onset of atopic dermatitis and a predilection for skin lesions affecting the head and neck.⁸ 

Commonly misdiagnosed as poorly controlled eczema or atopic dermatitis with bacterial superinfection,^2,5 eczema herpeticum should remain high on the list of differential diagnoses in atopic children who present with a sudden onset of worsening skin disease manifesting as vesicles and erosions.

References:

1.Mackool BT, Goverman J, Nazarian RM. Case records of the Massachusetts General Hospital. Case 14-2012. A 43-year-old woman with fever and a generalized rash. N Engl J Med. 2012;366(19): 1825-1834.

2. Habif TP. Warts, herpes simplex, and other viral infections. In: Clinical Dermatology. 5th ed. Philadelphia, PA: Mosby Elsevier; 2010:454-490.

3. Leung DYM, Eichenfield LF, Boguniewicz M. Atopic dermatitis (atopic eczema). In: Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, eds. Fitzpatrick’s Dermatology in General Medicine. 7th ed. New York, NY: McGraw-Hill, 2008:146-158.

4. Sais G, Jucglà A, Curcó N, Peyrí J. Kaposi’s varicelliform eruption with ocular involvement. Arch Dermatol. 1994;130(9):1209-1210.

5. Moran PJ, Geoghegan P, Sexton DJ, O’Regan A. A skin rash to remember. BMJ. 2012;345:e6625.

6. Leung DYM. Why is eczema herpeticum unexpectedly rare? Antiviral Res. 2013;98(2):153-157.

7. Kimata H. Rapidly increasing incidence of Kaposi’s varicelliform eruption in patients with atopic dermatitis [letter]. Indian J Dermatol Venereol Leprol. 2008;74(3):260-261.

8. Peng WM, Jenneck C, Bussmann C, et al. Risk factors of atopic dermatitis patients for eczema herpeticum [letter]. J Invest Dermatol. 2007;127(5):1261-1263.