Introduction\RL:Small-bowel diverticulosis is an uncommon clinical entity, with ileal diverticula representing the rarest subtype. Unlike Meckel’s diverticulum, non-Meckelian ileal diverticula are typically acquired and arise along the mesenteric border due to mucosal and submucosal herniation through weak points in the muscular layer(1, 2). Their prevalence is estimated to be below 1% in the general population, and most remain clinically silent throughout life. When symptoms do occur, they often mimic more common abdominal pathologies, creating diagnostic uncertainty in emergent settings. Perforation is among the most serious complications and carries significant morbidity if diagnosis is delayed(3).Perforated peptic ulcer remains one of the leading causes of sudden-onset abdominal pain with free intraperitoneal air and is frequently the initial clinical consideration when pneumoperitoneum is detected. Classical symptoms abrupt epigastric pain, peritonitis, and radiographic free air often guide emergency physicians and surgeons toward a gastroduodenal source. However, pneumoperitoneum is not pathognomonic for peptic ulcer disease; perforations originating from small-bowel diverticulitis, although extremely rare, can produce nearly identical clinical and radiologic patterns(4, 5). This overlap can lead to significant diagnostic pitfalls, particularly when the patient is young and lacks significant risk factors for peptic ulcer disease. Younger patients pose an additional diagnostic challenge. Unlike older adults, in whom peptic ulcer disease and NSAID-related perforations are more prevalent, adolescents and young adults seldom present with perforated gastroduodenal ulcers unless clear risk factors exist(6). In such individuals, the presence of diffuse free air on imaging may be misleading, resulting in an anchoring bias toward a presumed upper gastrointestinal perforation. The rarity of ileal diverticulitis in this age group further contributes to diagnostic delay, as clinicians may not initially consider it in the differential diagnosis of acute abdomen(7).In this case report we described an 18-year-old male who presented with abdominal pain and CT findings highly suggestive of perforated peptic ulcer, yet intraoperative exploration revealed a perforated ileal diverticulum located approximately 50 cm proximal to the cecum. The unusual presentation, combined with overlapping radiologic features, exemplifies a rare but important diagnostic pitfall. By detailing the clinical course, imaging findings, and intraoperative observations, this report aims to highlight the need for heightened clinical suspicion for small-bowel sources of perforation, even in young patients, when pneumoperitoneum lacks a definitive upper gastrointestinal correlate. The present case report adheres to the SCARE criteria for the reporting of surgical case reports, ensuring methodological rigor and transparency(8).
