山口 和磨¹, 斎藤 聡², 伝法 秀幸¹, 窪田 幸一¹, 藤山 俊一郎², 小林 正宏², 橋本 雅司³, 木脇 圭一⁴

Kazuma YAMAGUCHI¹, Satoshi SAITO², Hideyuki DENPO¹, Koichi KUBOTA¹, Shunichiro FUJIYAMA², Masahiro KOBAYASHI², Masaji HASHIMOTO³, Keiichi KINOWAKI⁴

¹虎の門病院分院臨床検査部, ²虎の門病院肝臓センター, ³虎の門病院消化器外科, ⁴虎の門病院病理診断科

¹Department of Clinical Laboratory, Toranomon Hospital, ²Department of Hepatology, Toranomon Hospital, ³Department of Gastroenterological Surgery, Toranomon Hospital, ⁴Department of Pathology, Toranomon Hospital

キーワード : steatohepatitic hepatocellular carcinoma, retrospective study, ultrasonography, high echoic pattern, B-mode findings

目的：2019年版WHO分類で新たに肝細胞癌の亜型とされた，Steatohepatitic hepatocellular carcinoma （SH-HCC）に関して超音波所見を中心に臨床病理学的な検討を行いBモード像の特徴を明らかにする．対象と方法：対象は2015‐2019年に治癒切除された肝細胞癌477例中，SH-HCCを有する71例．SH-HCC成分が50％以上である典型群34例，それ以下の限局群37例であった．後ろ向きに超音波Bモード画像を中心に臨床病理学的検討を行った．結果と考察：典型群は直径中央値18mmで中分化型肝細胞癌が大部分であり，高エコーパターンが67％でnodule in noduleパターンが33％であり，辺縁低エコー帯83％，lateral shadow80％，acoustic shadowを87％に認めた．ダイナミックCT・MRIでは多血性で造影剤のwashoutもみられ，脂肪化を伴う肝細胞癌の一般的な所見であった．一方，限局群では超音波医学会の，肝腫瘤の超音波診断基準と合致する所見を呈する結節が69％であった．共に背景肝は線維化進行例が多く，1/3程度は脂肪肝を伴い，Bモード所見に影響がみられ，超音波で描出困難例は10％台であった．結論：典型的なSH-HCCは特徴的なBモード所見を呈し，超音波像がSH-HCC鑑別の一助となる可能性が示唆された．

Purpose: Steatohepatitic hepatocellular carcinoma (SH-HCC) is a newly described subtype of HCC as defined in the 2019 World Health Organization (WHO) classification of tumors. In this study, ultrasound and clinicopathologic studies were conducted on patients who were diagnosed with SH-HCC. SH-HCC has been associated with liver cancer resulting from fatty liver disease; this condition has been identified in an increasing number of patients in recent years. Subjects and Methods: This study included 34 patients in the typical SH-HCC group (7%) and 37 patients in the focal SH-HCC group (8%) out of 477 patients who underwent curative resection of untreated HCC during 2015-2019. We conducted a retrospective clinicopathological study focusing on ultrasound B-mode images. Results and Discussion: The median diameter of the lesions associated with typical SH-HCC was 18 mm. Most of the HCCs were moderately differentiated: 67% exhibited a hyperechoic pattern, 33% presented with a nodule in a nodule pattern, and 83% had a marginal hypoechoic layer. A lateral shadow was detected in 80% of the tumors. Acoustic shadows appeared in 87%. Dynamic computed tomography/magnetic resonance imaging revealed hypervascularity in the arterial phase and washout of contrast medium during the late portal phase; these findings are consistent with normal HCC with fat deposition. By contrast, 69% of those from the focal group presented with findings that were consistent with the ultrasound diagnostic criteria of the Japan Society of Ultrasonics in Medicine for nodules associated with hepatic masses. In both cases, the background liver tissue was notable for advanced fibrosis. Approximately one-third of the background liver tissue included findings consistent with fatty liver; this had a significant impact on B-mode findings or generated difficulties with visualization in the 10% range. Conclusion: Typical SH-HCC showed characteristic B-mode findings, which showed that it is possible to distinguish SH-HCC using ultrasonic images.