A 73-year-old man with a 2- to 3-week history of herpes zoster in the left T11-T12 dermatomes developed a painful, progressive bulge in his left flank. The bulge was more prominent on standing, coughing, and straining. Antiviral agents were not administered when he first developed zoster because the diagnosis was established more than 72 hours after first presentation of the disease. Neither fever nor chills were reported. The patient’s medical history was notable for a 30-year history of hypertension and diabetes. Physical examination revealed a reducible protrusion in the left flank, with several red to light brown macules on the overlying skin (Figure). Computed tomography (CT) of the abdomen showed convexity of the left lower abdominal wall compared with the right and did not reveal any mass, hernia, or accumulation of fluid in the abdominal cavity.