Disseminated Cutaneous Herpes Zoster in an Immunocompetent Patient: A Diagnostic Challenge

Disseminated cutaneous herpes zoster (DCHZ) typically occurs in immunocompromised individuals. However, rare cases arise in immunocompetent adults. These cases may initially resemble benign dermatoses or be difficult to distinguish from other systemic rashes when overlapping risk factors obscure diagnosis. Early recognition is essential to prevent visceral or neurologic complications. A 32-year-old immunocompetent male with childhood varicella presented with a 10-day history of a pruritic vesicular rash, right ear fullness, and viral prodromal symptoms. He had recent diving exposure five days prior. The eruption began with axillary myalgia progressing to vesicles spanning multiple right thoracic dermatomes, eventually extending anteriorly. Folliculitis was excluded due to non-pustular morphology and preceding neuropathic discomfort. Decompression-related skin injury was ruled out, given symptom onset and absence of cutis marmorata. Physical examination demonstrated grouped vesicles beyond contiguous dermatomes, consistent with DCHZ. The patient was treated with valacyclovir and gabapentin. DCHZ in immunocompetent adults is uncommon but may lead to systemic complications. Misdiagnosis is possible when early lesions mimic folliculitis or irritant dermatoses. If relevant risk factors are present, such as recent deep or prolonged diving exposure or inadequate decompression, the presentation may have other cutaneous changes, making clinical differentiation challenging. Key distinctions in lesion morphology, distribution, and associated neuropathic symptoms are essential for separating these mimickers and recognizing disseminated varicella-zoster virus (VZV) promptly. This case highlights that disseminated cutaneous herpes zoster may occur in healthy adults and underscores the importance of early diagnosis and prompt antiviral therapy, particularly when risk factors are present, and lesion morphology mimics benign conditions.