特異なCT・エコー画像を呈したサルモネラ菌による感染性偽性胸部大動脈瘤の1救命例

A Case of Mycotic Pseudoaneurysm of the Thoracic Aorta due to Salmonella Infection Presenting Peculiar Computed Tomographic and Echocardiographic Findings

　症例は約10年来の糖尿病，高血圧歴をもつ67歳の男性．2週前より40℃に達する弛張熱と上腹部痛が出現し入院となった．入院時白血球数（10,100／μl）とCRP値（17.7mg／dl）の高値を認め，細菌の動脈血培養は陰性であったが血中エンドトキシンの上昇を認めたため，消化器系の検索を進めたが発熱のfocusは不明であった．入院第9病日の胸部造影CTにて，内部が三葉に造影される下行大動脈の瘤状の拡大を認めたため，感染性動脈瘤の疑いにて同日胸部外科転院となった．経食道エコーにて大動脈破裂，および破裂口を覆う多量の血腫を認め，緊急手術となった．血腫の細菌培養からサルモネラ菌が検出され，サルモネラ菌感染による偽性大動脈瘤と診断された．サルモネラ性胸部大動脈瘤は極めて稀であり，本例のようにCT・エコー上特異な画像所見を呈した偽性動脈瘤の報告は見あたらず，貴重な症例と思われた．

A 67-year-old man was admitted to our hospitalbecause of fever and epigastralgia which had lasted fortwo weeks. He had had a history of diabetes and hyper-tension for ten years. On admission, laboratory studiesshowed elevation of the white blood cell count (10,100/μl), and increase of C-reactive protein (17.7mg/dl) andendotoxin level. Several blood cultures for bacteriawere negative. Examination of the digestive systemfailed to detect the origin of the fever. The contrast-enhanced CT of the chest on the 9th hospital dayrevealed peculiar dilatation of the descending aortawhich had three cavities enhanced by contrast medium.We considered mycotic aneurysm as a diagnostic possi-bility and referred the patient to the department ofthoracic surgery at another hospital. Since transesopah-geal echocardiography showed rupture of the descend-ing thoracic artery surrounded by a large amount ofthrombus, an emergency operation (grafting) wasperformed. A culture of the thrombus yielded salmonel-la, and a diagnosis of mycotic pseudoaneurysm due tosalmonella infection was established. Salmonellamycotic aneurysms of the thoracic aorta are very rare,and CT findings and results of echocardiography such asthose in this case have never been reported. Althoughthe patient became paraplegic immediately after theoperation, he is still alive 8 months after the operationwithout recurrence.