Pseudohernia Following Herpes Zoster Presenting With Transient Abdominal Wall Bulging: A Case Report.

Herpes zoster (HZ), caused by reactivation of latent varicella-zoster virus within the sensory ganglia, typically presents with painful vesicular eruptions. While motor nerve involvement is uncommon, it can occasionally lead to abdominal wall pseudohernia. Pseudohernia results from denervation and paralysis of abdominal muscles in the absence of a fascial defect, and is easily mistaken for a true hernia. We report the case of a 78-year-old man who developed a left-sided abdominal wall bulge shortly after the onset of HZ rash in the T10-T12 dermatomes. The bulge became prominent when standing but diminished in the supine position. CT revealed asymmetric thinning of the internal oblique and transversus abdominis muscles at the T11 level, with preservation of fascial continuity and no protrusion of intra-abdominal contents. These findings, combined with the close anatomical correspondence between the skin rash and the innervation of affected muscles, supported the diagnosis of HZ-related pseudohernia. Differential diagnoses such as diabetic truncal neuropathy, postsurgical changes, scarring myopathy, and localized fat atrophy were considered but excluded based on clinical history and imaging. The patient was managed conservatively with antiviral therapy and neuropathic pain control, leading to complete resolution of the bulge within three months. This case emphasizes that when abdominal wall bulging occurs near recent HZ skin lesions, pseudohernia should be strongly suspected. Recognition of this condition is essential to avoid misdiagnosis and unnecessary surgical procedures. Diagnosis can be supported by both clinical findings, including reduction of the bulge in the supine position, and imaging evidence of muscle thinning without a hernial defect. Prognosis is generally favorable, as most patients recover with conservative management alone.