岡庭 信司¹, 岩下 和広², 井上 貞孝²

Shinji OKANIWA¹, Kazuhiro IWASHITA², Sadataka INOUE²

¹飯田市立病院消化器内科, ²飯田市立病院超音波室

¹Department of Gastroenterology, Iida Municipal Hospital, ²Division of Ultrasound, Iida Municipal Hospital

キーワード : ultrasound, cancer screening, pancreatic ductal carcinoma, high-risk group

超音波検査は簡易で低侵襲な検査であるため，人間ドックや集団検診といったスクリーニングにも広く用いられており，膵嚢胞や膵管拡張は比較的よく遭遇する超音波所見である．一方で，超音波検査の診断能は検査担当者の技能や知識に依存することから，検査担当者は標準的な走査法に習熟し鑑別診断に有用な超音波所見を熟知することが必要である．膵病変は充実性病変と嚢胞性病変に分類され，充実性病変には膵管癌，神経内分泌腫瘍，SPN（solid-pseudopapillary neoplasm），腫瘤形成性膵炎などが，嚢胞性病変には漿液性嚢胞性腫瘍（serous cystic neoplasm: SCN），粘液性嚢胞性腫瘍（mucinous cystic neoplasm: MCN），膵管内乳頭粘液性腫瘍（intraductal papillary mucinous neoplasm: IPMN）などが含まれる．今回は膵臓の描出法と見落としやすい部位，膵管拡張や嚢胞性病変といった膵管癌の高危険群，さらに膵管癌と他の充実性病変の鑑別点につき解説する．

As ultrasound (US) is a simple and less invasive modality, it is widely used for mass screening. Both pancreatic cysts and dilated pancreatic ducts are common findings. As the diagnostic accuracy of US depends on the operator's skill and knowledge, sonographers should master the standard scanning method and learn characteristic US findings for the differential diagnosis. Pancreatic neoplasms are generally classified as solid or cystic. The solid neoplasms include pancreatic ductal carcinoma, neuroendocrine tumor, solid-pseudopapillary neoplasm (SPN), and tumor-forming pancreatitis. The cystic neoplasms include serous cystic neoplasm (SCN), mucinous cystic neoplasm (MCN), and intraductal papillary mucinous neoplasm (IPMN). First, we explain the basic scanning method and pitfalls of US imaging of the pancreas. Second, we highlight the high-risk group including dilatation of pancreatic ducts, cystic lesions, and so on. Third, we illustrate the differential diagnosis between ductal carcinomas and other solid lesions.