CLINICAL HISTORY:

Signs and symptoms:  7yo male with several month history of a pruritic red rash which occurs minutes to hours after sun exposure (Figures 1-3).

Previous Treatment:  Topical low potency steroids without success.

Other information:  Patient's mother later related that the patient suffers from frequent cold sores.

PHYSICAL EXAM:

Multiple annular and later targetoid plaques on face and trunk especially in sun exposed areas.

LABORATORY TESTS:

HSV IgG +

DERMATOHISTOPATHOLOGY:

Cell poor interface dermatitis with occasional dyskeratotic cells and viral cytopathic changes. EBV in-situ hybridization was negative. (Figures 4, 5)

DIFFERENTIAL DIAGNOSIS:

1.   Juvenile Spring Eruption
2.   HSV Induced Erythema Multiforme
3.   Drug induced Erythema Mulitforme
4.  
5.  

SCROLL DOWN FOR ANSWER AND DISCUSSION.

CORRECT DIAGNOSIS:

HSV induced photo erythema multiforme

DISCUSSION:

This case proved challenging at first with limited history and vague initial clinical and histopathological findings. Originally the child was histologically diagnosed with juvenile spring eruption. Not convinced of this diagnosis we had the child return with his mother and her additional history proved invaluable. The history of recurrent herpes labialis helped us along with maturation of the first rash into discrete targetoid lesions. All of these factors along with a negative EBV in-situ hybridization led us to the diagnosis and prompt institution of acyclovir.

HSV induced erythema multiforme is not a rare entity and its occurrence has been well documented and researched(1). Its exact cause remains a mystery but new data has pointed to a specific immunological phenomenon(2). EM like lesions often occurs with the presence of viral material in the skin(3). Photo-drug induced EM, a entirely different pathological process, has been reported in the literature, but no true HSV induced photo-EM has been reported.

This case was so unique in that the rash occurred only in photo distributed areas on the child. This should be considered part of any differential where there is a photo-distributed dermatitis.

TREATMENT:

Patient was started on acyclovir at 20mg/kg dose 4 times daily with rapid clearance. Strict and complete sun blockade was also encouraged. When the drug was stopped, the rash quickly returned with sun exposure.

REFERENCES:

Kokuba H, Aurelian L, Burnett J. Herpes simplex virus associated erythema multiforme (HAEM) is mechanistically distinct from drug-induced erythema multiforme: interferon-gamma is expressed in HAEM lesions and tumor necrosis factor-alpha in drug-induced erythema multiforme lesions. J Invest Dermatol. 1999 Nov;113(5):808-15.

Kokuba H, Imafuku S, Huang S, Aurelian L, Burnett JW Erythema multiforme lesions are associated with expression of a herpes simplex virus (HSV) gene and qualitative alterations in the HSV-specific T-cell response. Br J Dermatol. 1998 Jun;138(6):952-64.

Brice SL, Leahy MA, Ong L, Krecji S, Stockert SS, Huff JC, Weston WL Examination of non-involved skin, previously involved skin, and peripheral blood for herpes simplex virus DNA in patients with recurrent herpes-associated erythema multiforme. J Cutan Pathol. 1994 Oct;21(5):408-12

Additional Comment:

The authors would like to thank Michael Heaphy, MD and Theodore Schiff, MD for their assistance and guidance.

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