Transient Reticular Erythema After Thermotherapy - A Novel Sign to Early Diagnosis of Herpes Zoster: A Case Report

Abstract

Herpes zoster (HZ) is caused by the reactivation of the varicella-zoster virus, often presenting with prodromal neuralgic pain that precedes characteristic skin lesions by 1–5 days, complicating early diagnosis. This case report describes a novel dermatologic finding in a 52-year-old healthy female physician with a history of childhood varicella and prior HZ. She experienced progressive, burning pain in the right thigh and iliac fossa, initially without skin lesions. On day four, thermotherapy applied to the affected dermatome induced a transient reticular erythema resembling livedo reticularis (LR), which was absent in the unaffected limb. Subsequent Doppler ultrasonography ruled out vascular pathology, and empirical treatment for pelvic inflammatory disease was initiated. On day five, vesicles appeared in the L2-L3 dermatome, confirming HZ. Pain and paresthesia were managed with topical lidocaine, acetaminophen, and codeine, without antiviral therapy. To our knowledge, this is the first reported instance of transient reticular erythema triggered by thermotherapy during the HZ prodromal phase, suggesting possible autonomic or sympathetic dysfunction associated with viral reactivation. This observation may serve as an early HZ finding, warranting further investigation to validate its utility in differential diagnosis and clinical management.