RÉSUMÉ
BACKGROUND: Mucocele of the appendix is an infrequent event, representing 0.3%-0.7% of appendiceal pathology and 8% of appendiceal tumors. It is characterized by a located or diffuse distension of the appendix with a mucus-filled lumen. MATERIALS AND METHODS: We describe 35 cases of mucocele of the appendix diagnosed at Ramón y Cajal Hospital between January 1985 and January 2006. RESULTS: A total of 21 males and 14 females with a mean age of 52.7 years are described. Most cases manifested as abdominal pain located in right iliac fossa, but 2 cases were incidental findings at CT-scan and 1 at ultrasonography, performed for other reasons. In 4 cases, mucocele coexisted with colorectal cancer and was an incidental finding during laparotomy performed for tumor resection. Ultrasonography and computed tomography (CT) scan helped to achieve a correct diagnosis. Preoperative diagnosis of mucocele was achieved in 29% of the cases; 88% of patients underwent appendectomy, 2 had ileocecal resection, and 2 others underwent right hemicolectomy. Pathology revealed mucous hyperplasia in 34% of the cases, simple mucocele in 29%, cystadenoma in 31%, and cystadenocarcinoma in 2 patients. Two other patients developed adenocarcinoma of the cecum 12 and 33 months after surgery, and one patient developed pseudomyxoma peritonei after 62 months, causing his death. CONCLUSIONS: The pathologist is forced to do an exhaustive study, looking for inadvertent perforations that can change the good prognosis of mucocele. We recommend follow-up of all patients with mucoceles, because sometimes they are associated with colorectal neoplasms and recurrence as pseudomyxoma peritonei.