Sigmoid invasion as a late complication of mucinous cystadenoma of the appendix. Report of a case.

A cystic mass arising from the right iliac fossa was an incidental finding at laparotomy and was treated conservatively after a biopsy had shown no evidence of malignancy. Nine years later the patient presented with shock and colonic bleeding. A large cystic lesion arising from the vermiform appendix and invading the sigmoid colon was found and excised. Histologic examination indicated that the underlying lesion was an inflamed mucinous cystadenoma of the appendix. Frank invasion of viscera by such lesions has not previously been described. Complications of such lesions and their association with other colonic neoplasms are discussed.