Case Report: Abdominal pseudohernia preceding the herpes rash: a pre-eruptive diagnostic pitfall in herpes zoster

Herpes zoster is usually recognized by its painful dermatomal eruption, although its motor complications are often overlooked. Herpes zoster-associated abdominal pseudohernia is a rare segmental motor manifestation in which paresis of the abdominal wall muscles produces a unilateral bulge without a true fascial defect. In most patients with herpes zoster, the bulge develops 1 to several weeks after the rash; in a minority of patients, it precedes the eruption, creating a particular risk of misdiagnosis. Herein, we describe a 66-year-old man with controlled diabetes and hypertension who developed a painful left abdominal bulge 4 days before the appearance of skin lesions. Routine laboratory tests were unremarkable, and abdominal computed tomography results showed no fascial defect or alternative structural cause of the bulge. Four days after the appearance of the bulge, erythema and grouped vesicles developed over the left T10-T12 dermatomes without crossing the midline. Before the dermatology visit, the patient had undergone lamp-fire moxibustion of the affected area as a folk remedy, after which the lesions rapidly crusted and the patient developed extensive postinflammatory hyperpigmentation. No fresh vesicles were present at dermatologic examination. A presumptive clinical diagnosis of herpes zoster-associated abdominal pseudohernia was made based on the segmental abdominal bulge, dermatomal distribution of the skin changes, and the reported history of a vesicular eruption. With conservative management, the bulge markedly regressed within 3 months. This case highlights that a new unilateral segmental abdominal bulge, even when it precedes the characteristic rash, should prompt consideration of herpes zoster to avoid unnecessary surgical intervention.