부산대학교 도서관

A 69-year old man who had a past history of undergoing an operation for fistula-in-ano at the age of 64, consulted a nearby hospital because of a one-month history of an anal induration. Because magnetic resonance imaging (MRI) scan showed a large cystic lesion 7cm in maximum diameter in the retrorectal space, he was introduced to our hospital. Fine needle aspiration cytology (FNAC) from the cystic lesion suggested benign mucinous fluid. But tumor markers CEA and CA19-9 were as high as 129 ng/ml and 87 U/ml, respectively and a part of the cystic lesion had SUVmax4.4 accumulation in FDG-PET. Colonoscopy revealed no membranous lesion in the rectum. Considered a possibility of malignant lesion, he was referred to our division for an elective operation. During 4 months of observation, the cystic lesion was enlarged rapidly to a size of 16×10 cm in diameter from around the rectum to under the rectus abdominis muscle via retroperitoneum. Although resection of the tumor via abdomino-spincteric approach and sigmoid colostomy were performed, the tumor was not completely resected due to its firm adhesions to the posterior surface of pubic bone and left obturator foramen. The definite histological diagnosis was well differentiated mucinous carcinoma, which was possibly derived from tailgut cyst because of localization of the tumor and his clinical course.