Ruptured Appendiceal Diverticulum Presenting as Appendiceal Phlegmon Mimicking Acute Appendicitis: A Case Report.

Appendiceal diverticulosis is a rare condition, with a reported incidence ranging from approximately 0.004% to 2.1%, and it may remain clinically silent or present with inflammation that closely resembles acute appendicitis. Distinguishing appendiceal diverticulitis from typical appendicitis preoperatively is often challenging because clinical manifestations and imaging findings are frequently nonspecific and may suggest an appendiceal phlegmon or localized perforation rather than a separate diverticular pathology. Definitive diagnosis is usually established by histopathological examination following appendectomy, which is also essential for assessing perforation and for excluding associated neoplastic changes. We report the case of a 34-year-old female who presented with right lower quadrant abdominal pain, nausea, and clinical findings consistent with acute appendicitis. Radiological evaluation suggested appendiceal inflammation with associated phlegmon formation. The patient underwent surgical intervention, and intraoperative findings revealed a ruptured appendiceal diverticulum with adjacent inflammatory changes. Histopathological examination confirmed perforated appendiceal diverticulitis with no evidence of malignancy. The postoperative course was uneventful, and the patient recovered well. This report highlights the importance of considering appendiceal diverticulitis in the differential diagnosis of acute right lower quadrant pain and emphasizes the role of careful histopathological evaluation after appendectomy to ensure accurate diagnosis and appropriate management.