臨牀消化器内科 Vol.34 No.12(1-2)

特集名	遭遇の機会が増えたIPMN/膵囊胞―現状と課題
題名	IPMNの基礎知識 (2) IPMN の病理
発刊年月	2019年 11月
著者	池田恵理子	自治医科大学病理診断部／自治医科大学内科学講座消化器内科部門
著者	福嶋敬宜	自治医科大学病理診断部
【要旨】	膵管内乳頭粘液性腫瘍（intraductal papillary mucinous neoplasm；IPMN）の病理学的概念は，多くの症例，議論を基に確立してきた．IPMNは腫瘍上皮の異型性による異型度分類と腫瘍の組織分化の種類による組織亜型分類がある．異型度分類は低異型度（low‒grade）と高異型度（high‒grade）の2段階であり，低異型度は腺腫（adenoma），高異型度は非浸潤癌（non‒invasive carcinoma）に相当する．組織亜型は，胃型，腸型，胆膵型，オンコサイト型に分類される．組織亜型の補助診断は，MUCシリーズ染色が有用である．IPMNに関わる遺伝子異常としてGNAS変異，KRAS変異，RNF43変異が判明している．とくにGNAS変異はIPMNに特異的な遺伝子異常であり，IPMN由来膵癌の鑑別診断にも有用である．また，良悪性の鑑別や治療方針決定の補助診断として，膵液を用いてGNAS変異の検出や組織亜型の判別を行う試みがされている．

Theme	IPMN/Pancreatic Cyst as an Increasing Common Disease -- Current Status and Issues
Title	Pathology of Intraductal Papillary Mucinous Neoplasm (IPMN)
Author	Eriko Ikeda	Department of Internal Medicine, Division of Pathology, Jichi Medical University / Department of Internal Medicine, Division of Gastroenterology, Jichi Medical University
Author	Noriyoshi Fukushima	Department of Internal Medicine, Division of Pathology, Jichi Medical University
[ Summary ]	In recent years, intraductal papillary mucinous neoplasm (IPMN) has increased and the pathological concept has been established. Histological grading and subtyping are important for pathologic diagnosis in IPMN. IPMNs are classified into low grade (same as "adenoma") and high grade (same as "non‒invasive carcinoma") according to their histological atypia, and into gastric, intestinal, pancreatobiliarty and oncocytic subtypes based on their cellular differentiation. MUC stains are useful for their histological subtyping. IPMN frequently harbor somatic mutations in GNAS, KRAS and RNF43 genes. GNAS gene mutation is relatively specific molecular alterations in IPMN and is uncommonly detected in pancreatic ductal carcinoma (PDAC). Pancreatic juice cytology with MUC Stains was reported to be useful for preoperative decision making.