Superinfected appendiceal mucocele with a giant appendicolith: a rare entity in a common surgical emergency – a case report

Introduction: Appendiceal mucocele (AM) is a rare surgical emergency, commonly caused by an appendicolith. An appendicolith larger than 2 cm is termed “giant,” which is rare and carries a high risk of perforation. This case highlights the diagnostic and surgical challenges of a superinfected AM complicated by a giant appendicolith. Case presentation: A 25-year-old woman presented to our emergency department with a 12-hour history of right lower quadrant pain, non-bilious vomiting, and fever with chills and rigor. On examination, her right iliac fossa was tender with rebound tenderness and a positive psoas sign. Ultrasonography showed an AM and an accompanying appendicolith. Computed tomography showed a hyperdense calculus measuring approximately 24 × 22 mm at the base of the appendix, with a maximum appendiceal diameter of 22.6 mm. Open appendectomy was performed, and histopathological examination found no signs of mucosal hyperplasia or neoplasia. Discussion: The coexistence of a superinfected AM with a giant appendicolith is exceptionally rare. Preoperative imaging findings, including an appendiceal diameter of more than 15 mm and peri-appendiceal fat stranding, raised the suspicion of mucinous neoplasm; however, the absence of mural nodularity and wall irregularity ruled out malignancy. Open appendectomy was performed to minimize the risk of mucocele rupture and pseudomyxoma peritonei. Histopathological examination remained the definitive diagnostic modality. Conclusion: A superinfected mucocele presenting with a giant appendicolith is extremely rare and poses a diagnostic challenge. Early surgical intervention using an open approach is recommended to prevent rupture and the catastrophic complication of pseudomyxoma peritonei. This case highlights the importance of vigilant clinical and radiological evaluation in such presentations.