Primary ileal adenocarcinoma presenting with perforation and peritonitis: a case report of a rare surgical emergency

Introduction: Adenocarcinoma of the small intestine is uncommon, with the ileum being a particularly rare site of origin. Its nonspecific clinical features often result in delayed diagnosis. Presentation as bowel perforation with peritonitis is extremely rare. Case presentation: We report the case of a 35-year-old female who presented with acute abdominal pain and signs of generalized peritonitis. Emergency laparotomy revealed multiple perforations with gross thickening of the wall in the distal ileum accompanied by peritoneal contamination. Segmental resection and locoregional lymph node dissection with primary ileo-ileal anastomosis and proximal diversion loop ileostomy were performed. Histopathological examination confirmed poorly differentiated adenocarcinoma infiltrating up to the surrounding stroma along with vascular invasion. The postoperative course was uneventful, and the patient was subsequently referred for adjuvant chemotherapy (FOLFOX regimen). Genetic counseling and microsatellite instability testing were recommended given her young age. Discussion: Ileal adenocarcinoma accounts for a small fraction of gastrointestinal cancers and is difficult to diagnose preoperatively due to vague symptoms and the poor sensitivity of imaging for small bowel tumors. Perforation of ileal adenocarcinoma is a rare but life-threatening complication requiring urgent surgical management. A literature review demonstrates very few reported cases of ileal adenocarcinoma presenting with perforation. Conclusion: Primary ileal adenocarcinoma should be considered in the differential diagnosis of small bowel perforation. Prompt surgical intervention, accurate staging, and genetic evaluation are vital for optimal management. This case underscores the need to suspect small bowel malignancy in unexplained perforations, even in young adults.