Grouped vesicles on an erythematous base should prompt concern for herpes viruses including varicella zoster (VZV) and herpes simplex (HSV). Polymerase chain reaction (PCR) testing for both VZV and HSV revealed this to be sacral HSV.
VZV classically presents in a dermatomal distribution, whereas HSV more commonly manifests along a single peripheral sensory nerve. Zosteriform presentations of HSV, however, have been reported.
Nongenital and nonoral HSV aren’t uncommon and can be associated with genital herpes, whether from self-inoculation or viremia.1 These outbreaks usually occur in the distribution of the pudendal nerve, which arises from the S2-S4 spinal nerves. There is an association of genital viral shedding even in the absence of lesions when sacral flaring manifests, and patients should be cautioned about sexual transmission or vertically transmitted perinatal infection in pregnant patients near term.
Treatment for an initial episode of genital infection with HSV is valacyclovir 1 g bid for 10 days. The regimen is ideally started within 48 to 72 hours of symptom onset.
This patient was empirically started on VZV dosing, then switched to HSV dosing when the PCR testing confirmed HSV. Knowledge of the exact pathogen is helpful in counseling the patient about the potential for spread and the risk of recurrence. With HSV, the patient may be prescribed a suppressive dose of valacyclovir 500 mg bid for 3 days, started at the onset of symptoms.
Text courtesy of Jonathan Karnes, MD, medical director, MDFMR Dermatology Services, Augusta, ME. Photos courtesy of Jonathan Karnes, MD (copyright retained).