かなり早期（動脈相）の造影CTだから門脈はまだ造影されていない．図２〜図４で左右肝内胆管が，図６〜図１０で総胆管（CBD）が拡張している．図１１で総胆管の造影効果が減弱し（↑），図１２では正常径の総胆管を認めるので図１１での閉塞だが，腫瘍性の病変か結石によるものかは鑑別できない．ERCPで閉塞部位（図A：▲）は腫瘍性病変と診断され，膵頭部十二指腸切除（PD：PancreatoDuodenectomy）を行った．病理：poorly differentiated adenocarcinoma．

参考症例（総胆管癌）：85歳女性．3日前背部に放散する心窩部痛が出現し，当日には発熱が加わり来院した．図１で肝内胆管（△）が，図３で総胆管が拡張し，胆嚢（GB）も腫大している．図５〜図８の↑が胆汁より高濃度を呈する閉塞病変であるが，結石か腫瘍かの鑑別はCTだけでは不可能である．図Aが切除標本で，▲が乳頭状の総胆管癌．病理：papillary adenocarcinoma．

文献考察：胆管腫瘍と結石の鑑別（表）
Radiographics. 2003 Mar-Apr;23(2):447-55.
Papillary neoplasms of the bile duct that mimic biliary stone disease.
Lim JH, Kim MH, Kim TK, Lee MG, Lee SS, Lee JW, Lee KT, Lee JK, Lim HK.

Papillary tumors of the bile duct are intraductal tumors with innumerable minute, frondlike papillary projections. These tumors may be either fixed to or detached from the bile duct wall. However, because the papillary projections on the surface of papillary tumors are long and slender, the tumors are friable and slough easily. The sloughed tumor fragments may float within the bile ducts, resulting in intermittent partial biliary obstruction and mimicking bile duct stones at clinical examination and at ultrasonography (US), computed tomography (CT), and cholangiography. A tumor manifests radiologically as thickening and irregularity of the bile duct wall or as a fixed or sloughed intraductal mass. A nonshadowing intraductal echogenic cast seen at US, an intraductal noncalcified soft-tissue mass with asymmetric wall thickening seen at CT, and an intraductal mass with a papillary surface and a serrated bile duct margin seen at cholangiography are all appearances that suggest a papillary tumor and may be helpful in differentiating a tumor from a bile duct stone. PMID: 12640158（full text）