倉澤 めぐみ¹, 伊東 敏弘², 岸 直子², 出口 直人¹

Megumi KURASAWA¹, Toshihiro ITOH², Naoko KISHI², Naoto DEGUCHI¹

¹禎心会病院臨床検査科, ²禎心会病院循環器内科

¹Department of Clinical Laboratory, Teishinkai Hospital, ²Department of Cardiology, Teishinkai Hospital

キーワード : mitral valve, myxoma, echocardiography, transesophageal echocardiography

生前診断例は稀と報告されている弁膜より発生する粘液腫を経験した. 症例は62歳, 男性. 既往である脳塞栓症の原因精査のため, 経胸壁心エコー図検査を行ったところ, 左房内に僧帽弁前尖に付着する約7×10 mmの腫瘤様エコーを認めた. このエコー所見は球状で内部不均一であった. さらに経食道心エコー図では同様の所見の他, 茎の有無や付着部位が明瞭に描出された. また内部エコーの性状については, 拡大画像により粘液質と思われる部分が数個の小さな嚢胞様低エコー域として描出され, 粘液腫に特徴のある所見と思われた. 新たな脳塞栓症の予防と確定診断のため, 外科的治療を選択した. 腫瘍は, ごく細い茎で付着していたため切離が容易であり, 自己弁を温存することができた. 組織診断は粘液腫であった. 腫瘍摘出6ヵ月後の経胸壁心エコー図検査では再発を認めていない.

Ante mortem detection of myxomas arising from the mitral valve has rarely been reported. We present a case of this condition in a 62-year old man with a history of cerebral embolism who was admitted to the hospital to determine its cause. Transthoracic echocardiography (TTE) detected a 7×10 mm tumor attached to the anterior mitral leaflet in the left atrium. The tumor appeared spherical and had heterogeneous internal echogenicity. Transesophageal echocardiography (TEE) clearly showed the stalk of the tumor and its attachment to the valve, consistent with the findings of transthoracic echocardiography. The characteristics of the internal echo, in which the mucouslike part was visualized as a small number of hypoechoic small cystic areas, could be interpreted as indicative of a myxoma. Surgery was carried out to establish a histologic diagnosis and prevent further cerebral events. The tumor was attached to the valve by a thin stalk and was readily resected; thus the original valve could be preserved. The histologic diagnosis was myxoma. Transthoracic echocardiography 6 months later showed no recurrence of the tumor.