BACKGROUND: Primary adenocarcinomas of the appendix are uncommon. Mucoceles that result from mucinous adenocarcinomas of the appendix may be incidentally detected on imaging.
CASE PRESENTATION: A case of a mucocele of the appendix, due to cystadenocarcinoma, is presented as an incidental imaging finding in a female, 86-year-old patient. The patient was admitted due to rectal hemorrhage and underwent colonoscopy, x-ray, US and CT. Adenocarcinoma of the ascending colon, adenomatous polyp of the sigmoid colon and a cystic lesion in the right iliac fossa were diagnosed. The cystic lesion was characterized as mucocele. The patient underwent right hemicolectomy, excision of the mucocele and sigmoidectomy. She recovered well and in two-year follow-up is free from cancer.
CONCLUSIONS: Preoperative diagnosis of an underlying malignancy in a mucocele is important for patient management, but it is difficult on imaging studies. Small lymph nodes or soft tissue stranding in the surrounding fat on computed tomography examination may suggest the possibility of malignancy.