胆管癌を合併した輪状膵の1例を経験した.症例は48歳男性で,急性胆嚢炎,閉塞性黄疸の診断で,近医で経皮経肝胆嚢ドレナージを施行後,紹介入院した.経皮経肝胆嚢ドレナージチューブ造影では下部胆管の全周性狭窄と壁硬化像を認め,更に,十二指腸の右側へ向かう膵管が造影された.低緊張性十二指腸造影では下行脚の限局性狭窄と口側腸管の拡張を認め,またcomputed tomographyでは十二指腸下行脚を取り囲む膵組織の存在が確認され輪状膵と診断した.下部胆管狭窄に対して悪性所見を強く疑い,手術を行った.術中迅速病理診断で胆管癌を確認し,手術は,幽門輪温存膵頭十二指腸切除,D,廓清を施行した.腫瘍は平坦浸潤型で,低分化な成分が混在し,胆管壁を浸潤性に増殖する中分化型腺癌であった.術後41日目に軽快退院し,3年後の現在,再発の徴候を認めていない.本邦報告例151例の成人型輪状膵を集計したところ,悪性腫瘍の合併は20例(13.2%)に認められ,このうち15例(75.0%)が膵胆道系の悪性腫瘍であった.輪状膵は膵胆道系の悪性腫瘍の合併が多いことを考えると,輪状膵の確定診断後は系統的な膵,胆道系の精査を行い,悪性腫瘍の存在の有無を確認することが必要と思われた.We experienced the case of a 48-year-old man suffering from an annular pancreas complicated with carcinoma of the bile duct. After the patient received percutaneous transhepatic gallbladder drainage (PTGBD) at a nearby hospital based on a diagnosis of acute cholecystitis and obstructive jaundice, he was referred to our hospital and admitted. Cholangiography performed by infusing a contrast medium through the PTGBD tube showed circumferential stenosis and parietal hardening of the lower bile duct and a pancreatic duct running to the right side of the duodenum. Hypotonic duodenography demonstrated stenosis localized in the descending part and dilatation of the intestinal tract on the oral side. Computed tomography (CT) showed the pancreatic tissue encircling the descending part of the duodenum. Based on these findings, he was diagnosed as having an annular pancreas with carcinoma of the bile duct. A surgical operation was performed because the stenosed site in the lower bile duct was strongly suspected of malignancy. The lesion was confirmed to be carcinoma of the bile duct through rapid intraoperative pathological examination, and pyloruspreserving pancreatoduodenectomy (PpPD) and D2 dissection were performed. The tumor, a flat, infiltrative type with intermingling, poorly differentiated components, was diagnosed as a moderately differentiated adenocarcinoma with infiltrative growth into the biliary wall. The patient remitted and was discharged on postoperative day 41. Now, three years after surgery, he shows no evidence of relapse. When we analyzed 151 cases of adult annular pancreas reported in Japan, 20 cases (13.2%) were found to be complicated with malignant tumors. Of these 20 cases, 15 (75.0%) had malignant tumors of the pancreatobiliary system. In view of the high incidence of malignant tumors of the pancreatobiliary system in patients with annular pancreas, it is imperative to rule out the presence of malignant tumors in these patients by systematically carrying out precise examinations of the pancreatobiliary system as soon as a definite diagnosis of annular pancreas is reached
