剖検にて明らかとなった腫瘍塞栓性肺微小血管障害(PTTM)の1例

A Case of Pulmonary Tumor Thrombotic Microangiopathy Revealed by an Autopsy

要旨　患者は74歳，女性．糖尿病・高血圧・脂質異常症のため前医通院中であった．2009年10月頃より労作時呼吸苦を認めるようになったため精査加療目的で受診した．諸検査の結果，心エコー検査で肺高血圧(推定肺動脈圧約80mmHg)を認め，肺高血圧症に伴う右心不全が呼吸苦の原因と考えられた．二次性肺高血圧症を示すような検査所見を認めず，肺動脈性肺高血圧症と診断し薬物治療を開始した．しかし，肺動脈圧に変化はなく右心不全が進行し症状発現から約4カ月の経過を経て死亡した．病理解剖の結果，進行胃癌が見出され肺動脈内に多発性腫瘍塞栓を形成しており腫瘍塞栓性肺微小血管障害(pulmonary tumor thrombotic microangiopathy;PTTM)に相当する所見と考えられた．PTTMは短期間で経過することが多いが，本例は比較的慢性の経過をたどり稀有な症例と考えられた．

　A 74-year-old female patient had been receiving treatment for diabetes mellitus, hypertension, and hyperlipidemia at another hospital. In October, 2009,she felt dyspnea on exertion and was referred to our hospital for close examination. On cardiac ultrasonography, mean pulmonary arterial pressure showed approximately 80mmHg. In order to exclude secondary pulmonary hypertension, various examinations were performed, but no significant findings were observed. From these results, we diagnosed that she had right cardiac failure due to pulmonary arterial hypertension and we started medical therapy. After starting therapy, right cardiac failure progressed and 4 months later she died of the disease that we initially diagnosed.

　The pathological autopsy revealed advanced gastric cancer forming multiple tumor emboli in the pulmonary arteries. These findings were considered to be consistent with pulmonary tumor thrombotic microangiopathy(PTTM)associated with pulmonary hypertension. It is rarely reported that the clinical course of PTTM has progressed as long as it did in the case which we encountered and have reported. If pulmonary hypertension of unknown cause is observed, malignancy should be suspected and its detection should be actively attempted.