Intestinal nonrotation with left-sided appendiceal microperforation mimicking colonic perforation: CT diagnostic pitfall and successful conservative treatment.

Intestinal nonrotation is an uncommon subtype of intestinal malrotation that may place the cecum and appendix in the left lower quadrant, creating a diagnostic pitfall in patients with left-sided abdominal pain. A 49-year-old man presented with a 3-day history of progressive left lower quadrant pain, fever, vomiting, and diarrhea. Contrast-enhanced CT demonstrated predominantly right-sided small bowel and left-sided colon, with the cecum and appendix located in the left iliac fossa. The appendix measured 9 mm in diameter and showed wall thickening, hyperenhancement, surrounding fat stranding, a suspected focal wall discontinuity, and adjacent tiny extraluminal air foci, findings strongly suggestive of appendiceal microperforation. The neighboring sigmoid colon showed mild focal wall thickening and fat stranding, a small localized abscess was also identified adjacent to the sigmoid colon, but no definite colonic wall defect, or inflamed diverticulum. After CT re-evaluation and surgical consultation, the initial concern for sigmoid perforation was revised to left-sided appendicitis with CT-suspected microperforation. Given the localized imaging findings and clinical stability, the patient was managed nonoperatively with antibiotics and close monitoring, with subsequent clinical and radiologic improvement. This case emphasizes the importance of identifying the malpositioned cecum and appendix, determining the inflammatory epicenter, and assessing the distribution of extraluminal air in patients with left lower quadrant pain.