Madam, appendiceal mucocele is an obstructive dilation of the appendix by intraluminal accumulation of mucoid material.1 Mucocele is an uncommon pathology encountered at a rate of 0.2% to 0.3% of all appendix specimens.1 Early diagnosis and prompt surgical intervention are mandatory to prevent perforation and spillage of the mucinous material into the peritoneal cavity causing pseudomyxoma peritonei.2 A 42-year-old female patient presented to our emergency department with right lower quadrant abdominal pain. Physical examination revealed a tender mass in the right lower quadrant without signs of peritonitis. WBC count was 12300/ml, and the other blood chemistry tests were normal. A transabdominal ultrasound examination showed a  plastrone appendicitis with free fluid in the region of the caecum. CT scan demonstrated a 6x4 cm heterogenous cystic mass  in the right lower abdominal quadrant, which suggested tubaovarian abscess or plastrone appendicitis. The patient underwent exploratory laparatomy. A firm, well-encapsulated  tumour was discovered at the radix of the appendix. It was mobilized from adjacent structures and removed intact (Figure). Histologically diagnosis was mucinous cystadenoma. Although widely used, the term mucocele is inherently imprecise and inclusive of both benign and malignant lesions.1,2 It may be caused by one of four processes: retention cyst, mucosal hyperplasia, mucinous cystadenoma, or mucinonous cystadenocarcinoma.1 Mucinous cystadenoma is defined as the dilated, mucous filled appendix containing hyperplastic adenomatous mucosa, with mucinous cystadenocarcinoma being present in majority of cases.2,3 In our case, mucocele caused by mucinous cytsadenoma was detected. Clinical manifestations of appendiceal mucoceles are nonspesific and one-quarter of them are asymptomatic.2 Presence of symptoms such as abdominal pain, abdominal mass, weight loss, nausea and vomiting, are associated with higher incidence of cystadenocarcinoma.1,2 The initial diagnostic modalities include ultrasound, barium enema, colonoscopy and CT scan.2 Diagnosis of mucocele is often confirmed by an abdominal CT scan, which is characterized by a well-encapsulated cystic mass 2 to 20 cm in diameter.1 In our case, CT scan demonstrated 6x4cm cystic mass, which could not be correctly diagnosed as mucocele, because plastrone appendicitis or tubaovarian abscess could not be excluded. All mucoceles should be removed to eliminate the chance of progression to malignancy.2 Appropriate therapeutic strategies are necessary to prevent perforation and spillage of the mucinous material into the peritoneal cavity causing pseudomyxoma peritonei.2-4 The type of surgical treatment is related to the dimensions and histology of the mucocele.2 In this case, the mucocele was removed intact without perforation and as the histological diagnosis was mucinous cystadenoma, no futher treatment was required.

Gülten Kiyak, Ali Çelik, Seyit Muhsin Sarikaya
Department of General Surgery, Atatürk Teaching and Research Hospital,
Bilkent, Ankara 06800, Turkey.
References
1.Dhage-Ivatury S, Sugarbaker PH. Update on the surgical approach to mucocele of the appendix. J Am Coll Surg  2006; 202: 680-4.
2.Korkolis DP, Apostolaki K, Plataniotis GD, Tzorbatzoglou J, Karaitianos IG, Vassilopoulos PP. Mucocele of the appendiceal stump due to benign mucinous cystadenoma. Anticancer Res 2006; 26: 635-8.
3.Marchiole P, Di Capua E, Costantini S. A right latero-pelvic mass: an uncommon diagnosis by endovaginal ultrasonoghraphy. Mucocele of the appendix. Acta Obstet Gynecol (Scand) 2006; 85: 1014-5.
4.Roberge RJ, Park AJ. Mucocele of the appendix: an important clinical rarity. J Emerg Med 2006; 30: 303-6.