[Mucocele of the appendix. Incidental sonographic discovery and laparoscopic resection].

History And Admission Findings: A 76-year-old currently asymptomatic man was admitted for routine sonography of the abdomen. 15 years he had had intermittently symptomatic cholecystolithiasis. 25 years before a colon contrast showed a normal coecum but no filling of the appendix.

Subsequent Investigation: Sonographic examination showed the known cholecystolithisasis but additionally revealed as an incidental finding a tubular-cystic structure with a thin, echogenic wall and a hypoechogenic lumen. The lesion was located in the right upper quadrant, not compressible and arising from the coecum. Computed tomography confirmed a mucocele of the appendix without ascites and no inflammatory changes, peritoneal thickening or nodules.

Treatment And Course: Laparoscopic resection of the unruptured appendiceal mucocele together with cholestectomy was performed. On gross examination, the resected mucocele proved to be macroscopally an intact mass with a thin wall and full of white gelatinous material measuring 3 cm in diameter and 8 cm long. The histologic diagnosis was mucinous cystadenoma. The patient was discharged on the second postoperative day and recovered uneventfully. Because of the clear association of appendiceal cystadenoma with colorectal tumor a colonoscopy was performed which showed a normal colon.

Conclusion: The differential diagnosis of a cystic mass in the right lower quadrant without previous appendectomy should include an appendiceal mucocele. If preoperatively there are no signs of malignancy, laparoscopic resection can be performed. In patients with histologic diagnosis of appendiceal cystadenoma: the colon should be examined to exclude synchronous colon tumors.