Fistula Formation Secondary to Mucinous Appendiceal Adenocarcinoma May Be Related to a Favorable Prognosis: A Case Report and Literature Review.

A 90-year-old man was referred to our hospital because of a positive fecal occult blood test. Colonoscopy revealed a lesion with multiple nodules covered with abundant mucus at the hepatic flexure. Computed tomography showed a dilated appendix attached distally to the hepatic flexure. Right hemicolectomy was performed, and the pathological examination revealed a mucinous appendiceal adenocarcinoma infiltrating the hepatic flexure without pseudomyxoma peritonei. The patient is doing well without recurrence 12 months postoperatively. Extraperitoneal drainage of the malignant ascites caused by the fistula may allow for an early diagnosis, while also making it possible to successfully resect the lesion, thus resulting in a favorable outcome.