植東 ゆみ¹, 松下 陽子¹, 岡山 幸成¹, 西村 理², 松末 智², 小橋 陽一郎³

Yumi UEHIGASHI¹, Yoko MATSUSHITA¹, Yukinari OKAYAMA¹, Satoru NISHIMURA², Satoru MATSUSUE², Yoichiro KOBASHI³

¹天理よろづ相談所病院臨床病理部, ²天理よろづ相談所病院腹部一般外科, ³天理よろづ相談所病院病理

¹Department of Clinical Pathology, Tenri Hospital, ²Department of General Surgery, Tenri Hospital, ³Department of Pathology, Tenri Hospital

キーワード : leiomyoma, splenic vein, ultrasound

脾静脈に発生した平滑筋腫の1例を経験したので腹部超音波検査（以下，US）像を中心に報告する．症例は61歳，男性．検診のUSで膵腫瘍を指摘され，精査を指示されて当院を紹介受診となった．USで膵体部相当部に40mm大の境界明瞭，内部に高エコー域を混ずる低エコー腫瘤を認めた．膵管の拡張は無く，脾静脈は圧排され，周囲に側副血行路の発達を認めた．開腹所見で，腫瘍は膵からは容易に剥離出来たが，脾静脈と融合しており，脾静脈合併腫瘍切除術が施行され，病理組織学的に脾静脈原発平滑筋腫と診断された．RetrospectiveにUS像を見直すと，脾静脈にbeak signが見られ，腫瘍の発生部位を特定する着眼点と考えられた．

A 61-year-old man was referred to our hospital complaining of pancreatic tumor. Ultrasonogram (US) showed a tumor at the site of the pancreas body. The tumor was 40 mm in diameter, having a clear margin and a hypoechoic internal echo mixed with high echo areas, and the main pancreatic duct was not dilated. Additionally, the splenic vein was not depicted near the tumor, and collateral veins were found around the tumor on US. Laparotomy revealed that the tumor could be easily dissected from the pancreas but it was fused with the splenic vein. Excision of the tumor with the undetachable splenic vein was performed. The tumor was histologically diagnosed as leiomyoma of the splenic vein. Review of US showed the “beak sign” at the splenic vein, a finding that might be clue to help differentiate the site of the tumor.