PCR-confirmed disseminated herpes zoster initially mimicking lumbar radiculopathy in an apparently immunocompetent adult: a case report and literature review.

Background: Disseminated herpes zoster (DHZ) is typically associated with impaired cell-mediated immunity and is uncommon in adults without an identified immunocompromising condition. Diagnostic delay may occur when prodromal dermatomal pain precedes rash and mimics structural spine disease. Case Presentation: A 59-year-old woman presented with 6 days of intermittent burning and needle-like pain involving the left thigh and calf and was initially diagnosed with lumbar disc herniation after lumbar CT showed multilevel degenerative disc protrusions. Lumbar traction was performed during this period, while the pain continued to worsen. Two days before admission, vesicular lesions appeared on the left thigh and rapidly extended to the back, buttock, perineum, scalp, face, trunk, and limbs. Examination showed grouped vesicles and pustules with marked tenderness but no objective focal neurological deficit. VZV DNA PCR from vesicle fluid and peripheral blood was positive. Evaluation showed no evidence of HIV infection, malignancy, diabetes, or immunosuppressive therapy. Immune testing showed no quantitative T-cell deficiency and normal immunoglobulin levels. The patient was treated with intravenous acyclovir, gabapentin, and supportive care, with cessation of new lesions after 2 days and marked clinical improvement, with no recurrence or postherpetic neuralgia at 4-week follow-up. Conclusion: This case highlights that DHZ may rarely occur in an apparently immunocompetent older adult and may initially mimic lumbar radiculopathy when imaging shows incidental degenerative changes. Acute dermatomal neuropathic pain without objective neurological deficits should prompt consideration of herpes zoster even before rash appears.