年森 明子¹, 宮田 英樹¹, 相引 利彦¹, 奥平 知成¹, 畔元 信明¹, 平岡 淳¹, 二宮 朋之¹, 前田 智治², 河崎 秀樹³, 道堯 浩二郎¹

Akiko TOSHIMORI¹, Hideki MIYATA¹, Toshihiko AIBIKI¹, Tomonari OKUDAIRA¹, Nobuaki AZEMOTO¹, Atsushi HIRAOKA¹, Tomoyuki NINOMIYA¹, Toshiharu MAEDA², Hideki KAWASAKI³, Kojiro MICHITAKA¹

¹愛媛県立中央病院消化器内科, ²愛媛県立中央病院病理診断部, ³愛媛県立中央病院消化器外科

¹Department of Gastroenterology, Ehime Prefectural Central Hospital, ²Department of Pathology, Ehime Prefectural Central Hospital, ³Department of Gastroenterological Surgery, Ehime Prefectural Central Hospital

キーワード : endoscopic ultrasonography (EUS), endoscopic ultrasonography fine-needle aspiration (EUS-FNA), pancreas neuroendocrine tumor (PNET)

症例は77歳，女性．増大傾向を示す胃粘膜下隆起または胃壁外性圧迫病変の精査目的に当院へ紹介された．造影CTでは膵体部に門脈相で最も強い内部均一な造影効果を有する直径25 mm大の類円形の腫瘤を認めた．MRIで同腫瘤は境界明瞭，内部均一でT1WI低信号，T2WI低信号．FDG-PET/CTでは軽度のFDG集積（SUV max 2.8）あり．超音波内視鏡（endoscopic ultrasonography: EUS）では，腫瘤は内部均一，境界明瞭で脾静脈を圧排し，辺縁に低エコー帯と，一部にそれに連続する低エコー性の部位を認め，被膜外浸潤を疑った．画像診断上，確定診断が得られず，EUS-FNA（endoscopic ultrasonography fine needle aspiration）を行い，pancreas neuroendocrine tumor（PNET）と診断して，膵体尾部切除を施行した．摘出標本は径28 × 26 mmで，腫瘍は線維性被膜を有し，一部に被膜外浸潤を伴っており，術前検査時にEUSで観察された一部肥厚した低エコー域と一致した．相当する部位はEUSでのみ描出でき，膵腫瘤診断におけるEUSおよび関連手技の有用性が確認された．

We encountered a 77-year-old Japanese woman with a pancreatic tumor revealed by computed tomography (CT) in the upper gastrointestinal fiber area. The tumor was enhanced slowly by CT, and shown to be a hypo-intense lesion with a clear border in T1- and T2-weighted magnetic resonance imaging. FDG-PET/CT findings showed that FDG uptake by the tumor was low (SUV max 2.6). Also, endoscopic ultrasonography (EUS) revealed a slightly low echoic tumor with a clear border and surrounded by a thin low echoic rim (1.0 mm), though part of the border area contained a hypoechoic rim that was rather thick (2.5 mm in width, 6.0 mm in length). A definitive diagnosis could not be made based on the imaging results. Fine-needle aspiration was performed, and we made a diagnosis of pancreatic neuroendocrine tumor (PNET). A distal pancreatectomy was performed. The resected tumor was measured to be 28 × 26 mm in diameter, and a fibrous capsule was found. Tumor cell invasion beyond the capsule was partially observed, and the capsule in this part was thick (2.5 mm in width, 5 mm in length). These findings of tumor invasion could be detected by EUS but not by the other modalities utilized. EUS and endoscopic ultrasonography fine-needle aspiration (EUS-FNA) are thought to be useful and essential for precise diagnosis of a pancreatic tumor.