Complete laparoscopic resection of giant appendiceal mucinous neoplasm, case report, and literature review

Abstract Introduction: Appendiceal mucinous neoplasms (AMNs) represent rare epithelial tumors of the appendix. While some cases are initially diagnosed due to appendicitis, the most prevalent presentation leading to a low-grade AMN (LAMN) diagnosis involves pain in the right lower abdominal quadrant within the context of acute appendicitis. The case presented here pertains to an unusually large LAMN (measuring 16 cm × 5 cm) that was successfully removed using laparoscopically assisted resection. Case Presentation: A 33-year-old female patient presented to the emergency department, complaining of abdominal pain and tenderness in the right lower quadrant and a palpable mass. A contrast-enhanced computed tomography (CT) scan of the abdomen and pelvis revealed a tubular, well-circumscribed, low-attenuation cystic lesion in the right iliac fossa. The lesion (measuring approximately 10 cm × 5 cm × 11 cm) appeared to originate from the lower medial aspect of the cecum. Magnetic resonance imaging (MRI) revealed a large (of about 16 cm × 5 cm dimensions), blind-ended tubular structure originating from the cecum. As LAMN was suspected, an emergency laparoscopic right hemicolectomy was performed, along with an end-to-end ileocolic anastomosis and lymph node (LN) dissection. During the surgery, a large appendicular mucocele with an impending risk of perforation was discovered. The final pathological diagnosis confirmed LAMN at stage pT3 with no LN involvement. Discussion: Although LAMN has an excellent prognosis, preoperative AMN diagnosis remains challenging. Thus, timely workup and management are crucial to prevent progression to pseudomyxoma peritonei (PMP) and metastasis. LAMN is usually diagnosed by examining CT scans, even though MRI is more effective in detecting peritoneal disease. While surgical resection is the only curative option for LAMN, surgical approach and LN dissection remains controversial due to the difficulty of preoperative malignancy diagnosis. Nonetheless, laparoscopic resection for LAMN can yield beneficial outcomes, but to prevent mucocele injury, surgeons should avoid direct tumor handling and ensure that clear margins had been attained, especially in invagination cases. Surveillance for recurrent disease and PMP after appendectomy is recommended, although there are no established guidelines regarding the surveillance frequency and duration. Conclusion: LAMN diagnosis is typically confirmed through surgical excision, whereby the choice of surgical approach depends on the stage of the disease and the surgeon’s experience. The standardization of postoperative follow-up and surveillance protocols for such cases is still in progress.