超音波内視鏡下穿刺吸引法が術前診断，術式選択に有用であった腹腔鏡下尾側膵切除術を施行した膵solid-pseudopapillary neoplasmの1例

A case of laparoscopic distal pancreatectomy for solid-pseudopapillary neoplasm of the pancreas in which endoscopic ultrasound-guided fine needle aspiration was useful for preoperative diagnosis and decision making for operative strategy

◆要旨：膵solid-pseudopapillary neoplasm （SPN）は低悪性度腫瘍で，多くが若年女性に発症し腹腔鏡下尾側膵切除術（LDP）の良い適応である．今回非典型的な画像所見を呈したSPNに対し，超音波内視鏡下穿刺吸引法（EUS-FNA）で術前診断し，LDPを施行しえた症例を経験したので報告する．患者は37歳，女性．腹部造影CTにて膵体部に遅延相で造影される35mm大の充実性腫瘤を認めた．内部に囊胞成分は認めなかった．画像所見のみでは開腹下でのリンパ節郭清を伴う膵切除を要する膵内分泌腫瘍，膵腺房細胞癌などとの鑑別は困難であり，EUS-FNAを施行した．EUS-FNAでは類円形の小型核を有する細胞が散見され，血管を軸にした乳頭状配列を示す小細胞塊が認められ，免疫組織染色でβ-cateninが核，細胞質に陽性でSPNと術前診断した．EUS-FNAは術式選択にきわめて有用であった．

Since solid-pseudopapillary neoplasm of pancreas（SPN） is a low grade maligant neoplasm and mostly occurrs in young woman, it is a good candidate for laparoscopic distal pancreatectomy （LDP）. The patient was 37-year-old woman. A contrast enhanced CT scan revealed a solid tumor with the size of 35mm in the body of the pancreas. An endoscopic ultrasound fine needle aspiration（EUS-FNA） was conducted because differential diagnosis was dificult to make with imaging study alone from other malignant pancreatic tumors including neuroendocrine tumor and acinar cell carcinoma, which may require radical open surgery. Our histopathological findings derived from the samples taken during EUS-FNA included the presence of cells with round nuclei that showed pseudopapillary growth. Immunoreactivity for β-catenin was found in the cytoplasm and nuclei of the tumor. EUS-FNA played the definitive role in making preoperative diagnosis of SPN. She underwent LDP. EUS-FNA was useful for preoperative diagnosis and decision making for the operative strategy in this patient, because the tumor presented with an atypical feature without cystic compartment.