Intussusception of the appendix by mucinous cystadenoma. Report of a case with an unusual clinical presentation.

Appendiceal mucocele is a very rare clinical condition. Associated ascites and an ovarian mass could suggest synchronous ovarian cystadenocarcinoma with pseudomyxoma peritonei. We describe the case of a 36-year-old female with a mucinous cystadenoma of the appendix causing intussusception, diagnosed by CT but not by US scan, since the associated anomalous fixation of the caecum was misleading in defining the precise anatomical site. Although the CT findings were accurate, the synchronous presence of an ovarian cyst and ascites did not allow us to rule out preoperatively a concurrent cystadenocarcinoma of the ovary with pseudomyxoma peritonei. The appropriate surgical treatment was performed on the basis of intraoperative frozen section examination. Surgical treatment depends on the nature of the mucocele: retention forms are effectively treated by appendectomy, while neoplastic conditions require a more extended resection. Treatment of associated ovarian cystadenocarcinoma and pseudomyxoma peritonei includes right colectomy, bilateral ovariectomy and omentectomy. Although a precise preoperative diagnosis of mucocele associated with intussusception of the appendix has been reported as possible, concomitant ascites and ovarian masses, as in the present case, could mimic pseudomyxoma peritonei from concurrent ovarian cystadenocarcinoma. Intraoperative histopathology is required in order to perform the most appropriate treatment.