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Sacral HSV Misdiagnosed as Zoster — SCE Infectious Diseases MCQ

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ModerateSTIsSacral HSV Misdiagnosed as ZosterSCE Infectious Diseases

A 30-year-old man presents with a cluster of grouped vesicles on an erythematous base on his right buttock in a dermatomal distribution (S2). He has no immunodeficiency. He has had 3 similar episodes in the past year in the same location. What is the diagnosis?

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Correct answer: E — Recurrent herpes simplex (HSV-2) — NOT herpes zoster; sacral dermatomal HSV recurrence is frequently misdiagnosed as zoster

Sacral dermatomal vesicular eruptions recurring multiple times in the same location are almost always HSV (usually HSV-2) rather than VZV. Key distinguishing features: HSV recurs in the SAME dermatome repeatedly; VZV zoster very rarely recurs in immunocompetent patients (lifetime recurrence ~5%). HSV sacral recurrence follows S2-S4 dermatomes and is caused by HSV-2 reactivation from sacral ganglia. Treatment is episodic or suppressive antivirals (Valaciclovir 500 mg BD for 5 days episodic; Aciclovir 400 mg BD daily for suppression). Viral PCR from a fresh vesicle confirms HSV vs VZV.

Reference: BASHH 2014 – Genital herpes; NICE CKS 2024 – HSV vs VZV