Appendiceal Diverticulitis Masquerading as Perforated Acute Appendicitis: Diagnostic Pitfalls With a Potential Computed Tomography Radiologic Clue.

We report the case of a 50-year-old man presenting with acute right lower quadrant pain and leukocytosis. Computed tomography suggested acute appendicitis with possible microperforation. Laparoscopic appendectomy revealed diverticulum-like outpouchings, and histopathology confirmed acute appendiceal diverticulitis with periappendicitis. Appendiceal diverticulitis is an uncommon but clinically significant entity due to its increased risk of perforation and possible association with neoplasia. The clinical and radiologic findings often mimic acute appendicitis, leading to under-recognition without careful review. In our case, a small gas locule seen on CT, initially interpreted as a microperforation, was retrospectively identified as a diverticulum. This finding highlights the potential diagnostic value of intramural gas micro-loculations and a saccular appendiceal contour on CT, particularly when combined with asymmetric periappendiceal fat stranding and wall thickening. Awareness of these imaging features may aid in distinguishing appendiceal diverticulitis from routine appendicitis, prompting appropriate surgical management and histopathologic assessment. Recognition of this condition is important for timely treatment and for guiding follow-up, given the associated risks.