Collision Tumor of the Appendix: Mucinous Cystadenoma and Carcinoid. A Case Report
D. Dellaportas, N.F. Vlahos, G. Polymeneas, G. Gkiokas, C. Dastamani, E. Carvounis, T. TheodosopoulosClinical case, no. 6, 2014
Introduction: Mucinous cystadenoma is the most common ofbenign neoplasms of the appendix and carcinoid is the mostcommon type of primary malignant lesions of the appendix.We report a rare case of a 57-year-old female with combinedmucinous cystadenoma and carcinoid tumor of the appendix.Dual carcinoid and epithelial neoplasia is a rare occurrencein the appendix.Case report: A 57-year-old Caucasian woman presented afterincidentally palpating a mass on her right iliac fossa. Imagingmodalities revealed a cystic tumor in the right iliac fossa with adiameter of about 8 cm, originating either from the right ovaryor the appendix. She underwent laparoscopic surgical exploration, which revealed appendiceal mucocele andappendicectomy was finally performed as well as excision of aright ovarian cyst. Pathological examination showed acollision tumor consisting of mucinous cystadenoma andcarcinoid tumor of the appendix. Because of the size andextension of the carcinoid tumor, which the pathology reportrevealed, she underwent re-exploration and laparoscopic rightcolectomy.Discussion: Mucinous cystadenoma is rare, but it is thecommonest of benign appendiceal tumours accounting for0.6% of appendectomy specimens. It can present as appendicitis,mucocele or if the tumour ruptures, as pseudomyxomaperitonei. On the other hand, carcinoid is the most commontype of primary malignant lesion of the appendix and 0.3-0.9%of appendectomy specimens, with small predominance infemale patients. Rare cases of mucinous cystadenomas of theappendix coexisting with carcinoid tumors were reportedbefore, but in our case it was a collision tumor with notransitional zone between them. Also, the clinical presentationof our patient and the differential diagnosis of ovarian lesionsfrom appendiceal tumors is worth being mentioned.
