[Mucinous cystadenocarcinoma of the appendix. Apropos of a case]

A case of mucinous cystadenocarcinoma discovered into a voluminous benign mucocele of the appendix, is presented. The clinical feature is a tumor of the right iliac fossa. The identification of a limited area of epithelial degenerescence in the cyst wall--by peroperative microscopic examination--permits immediate enlargement of the cystectomy by a right hemicolectomy. The prognosis of the tumor is generally excellent as soon as the diagnosis is early and the removal large enough.