EUS-FNAが術前診断に有用であった粗大な石灰化を伴う膵SPNの一例

A case of solid pseudopapillary neoplasm of the pancreas with massive central calcification

Creators Nakashima Takao

Creators Harima Hirofumi

Creators Kawano Michitaka

Creators Suenaga Shigeyuki

Creators Uekitani Toshiyuki

Creators Sen-yo Manabu

Creators Harano Megumi

Creators Kaino Seiji

Creators Suzuki Nobuaki

Creators Oka Masaaki

Creators Sakaida Isao

症例は46歳男性.検診の腹部超音波検査で肝腫瘍を指摘された.造影CTで肝腫瘍は血管腫と診断されたが,その際に膵腫瘤を指摘され当科に紹介となった.CTでは膵尾部に中心に粗大な石灰化を伴う2cm大の腫瘤を認めた.造影動脈相では造影効果に乏しかったが,平衡相では石灰化周囲の腫瘍辺縁近傍に周囲膵実質と同程度の造影効果を認めた.MRIではT1強調像で低信号,T2強調像で軽度高信号を示した.超音波内視鏡検査では中心に石灰化を有する境界明瞭な低エコー腫瘤として描出された.内部に嚢胞を疑う無エコーは認めなかった.以上の画像所見よりSolid pseudopapillary neoplasm(SPN)と神経内分泌腫瘍が鑑別に挙げられたが,いずれとしても非典型的であり,診断を確定する目的で超音波内視鏡下穿刺術を施行した.病理組織検査では,小型類円形核を有する腫瘍細胞の増生を認めた.免疫染色ではVimentin陽性,CD10陽性,β-catenin(核)陽性,Chromogranin A 陰性であった.組織構造が不明瞭で確定診断には至らなかったが,免疫染色のパターンからSPNが疑われた.腹腔鏡下脾温存膵体尾部切除術を施行し,切除標本の病理組織検査でSPNと最終診断した.術後10ヵ月現在,無再発生存中である.

Abdominal ultrasound revealed a liver tumor in a 46-year-old male during a medical screening, and a hemangioma on contrast-enhanced tomography (CT)and, a pancreatic mass were also found. The patient was then referred to our department for further evaluation and treatment. A 2cm tumor with massive central calcification was observed in the pancreatic tail. Although the contrast enhancement was poor in the arterial phase, the contrast enhancement was equal to that of the surrounding pancreatic tissue in the equilibrium phase. A low signal was displayed on T1-weighted magnetic resonance imaging (MRI),whereas a mildly elevated signal was displayed on T2-weighted MRI. During endoscopic ultrasonography(EUS),the tumor was visualized as a well-defined hypoechoic lesion with central calcification. Considering the above imaging findings, the differential diagnoses of solid pseudopapillary neoplasm(SPN)and neuroendocrine tumor were proposed. We performed endoscopic ultrasound-guided fine-needle aspiration(EUS-FNA)to obtain a definitive diagnosis. Hyperplasia of the tumor cells with small oval nuclei was observed upon histopathological examination. Immunostaining revealed that the tumor was positive for vimentin, CD 10 and β-catenin and negative for chromogranin A. SPN was suspected based on this immunostaining pattern. We performed laparoscopic spleen-preserving resection of the pancreatic body and tail. SPN was ultimately diagnosed during the histopathological examination of the resected specimen.

[ISSN]0513-1731

[NCID]AN00243156