池田 敦之¹, 田中 秀行¹, 中井 喜貴¹, 杉村 真弓², 松本 愛², 橋本 喜代美², 青木 由美子², 畦地 英全¹, 安原 裕美子³, 國立 裕之¹

Atsuyuki IKEDA¹, Hideyuki TANAKA¹, Yoshitaka NAKAI¹, Mayumi SUGIMURA², Ai MATSUMOTO², Kiyomi HASHIMOTO², Yumiko AOKI², Hidemasa AZECHI¹, Yumiko YASUHARA³, Hiroyuki KOKURYU¹

¹京都桂病院消化器センター消化器内科, ²京都桂病院消化器センター検査科, ³京都桂病院消化器センター病理診断科

¹Department of Gastroenterology and Hepatology, Kyoto Katsura Hospital, ²Department of Clinical Laboratory, Kyoto Katsura Hospital, ³Department of Pathology, Kyoto Katsura Hospital

キーワード : flat-infiltrating gallbladder cancer, liver invasion, contrast-enhanced ultrasonography, Sonazoid<SUP>&reg;</SUP>

64歳，男性．検診異常を機に発見された肝腫瘤を主訴に入院精査．CT，MRIで胆嚢に近接して肝S4に45 mm大の腫瘤性病変を認めたが，胆嚢の異常は指摘できず，肝内胆管癌や肝膿瘍が疑われた．腹部超音波検査では，S4に約6 cm大の類円形の腫瘤を認めた．境界はやや不明瞭で辺縁は整，内部は等‐高エコーの腫瘤であり，肝膿瘍は否定的であった．胆嚢には壁不整は指摘できず，隆起性病変も認めなかった．高周波プローブを用いた超音波検査で，胆嚢底部に肝腫瘤と連続する限局性の不整な壁肥厚を認めた．造影超音波検査で，腫瘤と胆嚢の壁肥厚は，動脈優位相において共に強い濃染を認めた後，腫瘍辺縁にリング状濃染を認めた．後血管相では明瞭な欠損像を呈した．以上の超音波所見より胆嚢癌肝浸潤と診断し切除術を施行．病理組織所見で肝腫瘤は，低分化型から中分化型の管状腺癌であった．胆嚢壁は全体に硝子化していたが，胆嚢内腔面にも低乳頭状を呈する分化型腺癌を認め，平坦浸潤型の胆嚢癌肝浸潤の所見であった．胆嚢床に存在する肝腫瘍は高周波プローブを用いた超音波で胆嚢との関係を詳細に観察することが有用である．また，胆嚢との連続性が疑われた場合は，造影超音波検査での血流評価が有用であると考えられた．

We report a case of flat-infiltrating gallbladder cancer with massive liver invasion. A 64-year-old man was referred to our hospital because a liver mass was detected by medical checkup. A liver mass 45 mm in diameter was shown next to the gallbladder by abdominal computed tomography (CT) and magnetic resonance imaging (MRI), but no remarkable elevated lesion in the gallbladder was shown by these images. Wall thickening and wall abnormality of the gallbladder were also not found. Based on these findings, we suspected intrahepatic cholangiocellular carcinoma (CCC) or liver abscess. Abdominal ultrasonography (US) showed a hyperechoic heterogeneous mass adjacent to the gallbladder. This finding was incompatible with liver abscess. US using a high-frequency probe visualized localized gallbladder wall thickening and continuity of the wall thickening with the liver mass. Contrast-enhanced US (CEUS) revealed hyper-enhancement of the liver mass and gallbladder wall thickening in the arterial phase. Ring enhancement was then shown around the liver mass. The liver mass was depicted as a contrast defect in the post-vascular phase. Based on the CEUS findings, gallbladder cancer was suspected rather than CCC. The final diagnosis was gallbladder cancer with liver invasion, for which surgical resection was performed. Histopathological study revealed that the liver tumor was a poorly to moderately differentiated adenocarcinoma. In the gallbladder, adenocarcinoma cells had spread widely, compatible with flat-infiltrating gallbladder cancer. In conclusion, US using a high-frequency probe would be a very useful to confirm the relation between liver tumors near the gallbladder and the wall of the gallbladder. And CEUS will be helpful to diagnose liver tumors adjacent to the gallbladder.