S4057 Benign Colonic Pneumatosis Presenting as Persistent Asymptomatic Pneumoperitoneum

Introduction: Pneumoperitoneum is traditionally regarded as a surgical emergency due to visceral perforation in 85%-95% of cases. However, benign pneumoperitoneum—free air without peritonitis or evidence of perforation—represents a rare diagnostic and management challenge, constituting only 5%–15% of all pneumoperitoneum cases. Asymptomatic presentations, as seen in this case, are exceedingly rare and underscore the importance of distinguishing benign etiologies from life-threatening pathology, particularly in patients with complex medical histories. Case Description/Methods: A 58-year-old man with a history of bicuspid aortic valve (BAV) and hypothyroidism presented for progressively worsening chronic constipation over the past 2 years, requiring daily glycerin suppositories. He reported intermittent non-painful left upper quadrant “stretching” sensations but no other symptoms. Of note, he received a course of high-dose corticosteroids for sudden sensorineural hearing loss (SSHL) 5 months prior. Initial computed tomography (CT) chest for his BAV assessment incidentally revealed focal pneumatosis of the proximal splenic flexure and associated free intraperitoneal gas. Subsequent CTA abdomen/pelvis confirmed intramural gas spanning the proximal splenic flexure wall with pneumoperitoneum. Notably, radiologic interpretation favored benign focal colonic pneumatosis, likely steroid-related, without evidence of mesenteric ischemia. Two months later, a follow-up CT abdomen/pelvis showed persistent but slightly decreased pneumatosis and pneumoperitoneum. Despite a stable clinical status, persistent pneumoperitoneum over 3 months prompted surgical intervention. Laparoscopic left hemicolectomy revealed an unusual perforation unrelated to common conditions like severe pneumatosis or diverticulosis. Pathology confirmed benign pneumatosis coli, and the patient recovered without major complications. Discussion: This case underscores the multifactorial nature of benign pneumoperitoneum. The temporal association between steroid administration for SSHL and subsequent pneumatosis strongly suggests possible steroid-induced mucosal vulnerability. Additionally, progressive chronic constipation likely increased intraluminal pressure, promoting microscopic mucosal injuries that facilitate gas penetration into the bowel wall. Despite a relatively benign clinical presentation, persistent pneumoperitoneum necessitated surgery. A laparoscopic approach minimized morbidity while providing definitive diagnosis and treatment.