Adenocarcinoma Arising in a Colonic Duplication Cyst: A Case Report and Review of the Literature
A 23-year-old female patient was admitted with a palpable abdominal mass. The mass had been noted three years previously. On physical examination, a nontender and movable mass measuring approximately 7 cm was observed at the right lower quadrant.\nThe patient's serum carcinoembryonic antigen (CEA) level was 6.51 ng/mL (normal range, <5.0 ng/mL), and that of cancer antigen 19-9 was 47.71 U/mL (normal range, <37 U/mL).\nUltrasonography disclosed a hypoechoic cystic mass with an internal echogenic dot in the right lower quadrant. The echogenic dot was thought to be either an intraluminal secretion or necrotic debris (). Computed tomography (CT) revealed a nonenhancing cystic mass measuring 7 cm, with linear calcification located adjacent to the medial side of the ascending colon (). No enlarged regional lymph nodes, ascites, or other abnormalities were observed.\nA laparoscopic excision of the mass was performed. During the operation, the mass was observed to be attached to the ascending colon mesentery, having the blood supply by the right colic artery.\nOn gross examination, the cystic mass measured 8.6×6.4×2.9 cm, and its outer surface was smooth; mesenteric fat adhered to the outer surface. The maximum thickness of the cystic wall was 1.5 cm, and focal calcification was noted within the wall. The cyst contained brownish-colored mucoid material ().\nMicroscopically, the cyst was found to have two well-organized layers of smooth muscle with an infiltrating adenocarcinoma forming irregular tubules (). The tumor had invaded the pericystic mesenteric soft tissue and metastasized to eight of 16 mesenteric lymph nodes. Perineural and lymphovascular invasions were noted. Non-neoplastic glandular epithelium was not found; instead, a focal area of atypical columnar epithelium, which was compatible with low-grade dysplasia, was observed (). On immunohistochemical study, tumor cells were positive for cytokeratin 7 (1:100, OV-TL 12/30, Dako, Glostrup, Denmark), cytokeratin 20 (1:100, KS20.8, Dako), CEA (prediluted, II-7, Dako), CDX2 (1:50, AMT 28, Novocastra, Newcastle upon Tyne, UK), and p53 (1:100, DO-7, Dako). The dysplastic epithelium was also positive for p53 ().\nPositron emission tomography-CT was performed after surgery and revealed no hypermetabolic areas other than the previous operation site. Two months after surgery, the patient started adjuvant chemotherapy.