Mucus containing cystic lesions "mucocele" of the appendix: the unresolved issues

Mucocele of the appendix is a rare condition, the pathological classification and management strategy of which have not been standardized yet.

To report on our management of appendiceal mucocele, highlighting the pitfalls and possible means for avoiding them.

Our registries were reviewed to retrieve cases of appendiceal mucocele, encountered in the period from July 2008 to May 2013.

We had 9 cases, three males and sex females, with a median age of 62 years. Abdominal ultrasound (US) and computerized axial tomography scan (CT) suspected the diagnosis in only one case each. Open appendectomy was done in two cases of mucinous cystadenoma with no further surgery performed, despite the positive margin in one. Laparoscopic appendectomy was done in three cases: mucinous cystadenoma in one case which needed no further surgery, mucinous cystadenocarcinoma with pseudomyxoma peritonei in another, and low grade mucinous tumour in a third case, and all needed subsequent right hemicolectomy. Exploratory laparotomy was done in three cases: of these, synchronous right hemicolectomy was done in one case of mucinous cystadenoma/?mucinous tumour of uncertain malignant potential; in the other two cases, appendectomy only was done for mucinous hyperplasia with carcinoid tumour of the appendix in one case and mucinous cystadenoma/?mucinous tumour of uncertain malignant potential in another. The 9th case was discovered upon laparoscopy for cholecystectomy; when pseudomyxoma peritonei arising from an appendiceal mucocele was found, laparoscopic appendectomy with peritoneal biopsy was then performed instead. Histopathologic diagnostic uncertainty was present in two cases of mucinous cystadenoma where mucinous tumour of uncertain malignant potential was an alternative possibility. Perioperative colonoscopy was performed in only one case and our follow-up programme was defective, with the longest period being 180 days.

Mucocele of the appendix should be considered in the differential diagnosis of cystic lesions in the right lower abdomen. Owing to its rarity, it continues to intrigue the surgeon as well as the radiologist and pathologist alike. For mucinous cystadenocarcinoma, right hemicolectomy is usually needed, whereas for hyperplasia and cystadenoma, appendectomy usually suffices if the resection margins are free. For mucinous tumours of uncertain malignant potential and low grade mucinous tumours as well as pseudomyxoma peritonei, the decision is not as simple. As for laparoscopic surgery, no solid proof exists with or against its safety. Although not yet standardized, perioperative colonoscopy and regular follow-up to detect early recurrences should probably be part of the management plan.