[A case of pulmonary thromboembolism due to circulating lupus anticoagulant]

A 22-year-old man was admitted because of hemosputum and progressive dyspnea with 3 attacks of chest pain and dyspnea over the previous 4 months. Chest roentgenography showed pulmonary infarction of the left lower lobe, and the diagnosis was confirmed by pulmonary perfusion and inhalation scintigraphy and pulmonary arteriography. Thrombolytic therapy was performed, but no significant effect could be obtained and anticoagulant therapy was performed continuously. No deep-vein thrombosis could be seen. He was considered to have autoimmune hemolytic anemia with lupus anticoagulant on the basis of auto-antibody data. Lupus anticoagulant is an antibody to phospholipid, and it is suggested that a decrease in the production of prostanoid in the endothelium causes thrombosis. In this case, as the patient showed a low level of 6-keto-PGF1 alpha in the blood, it is suggested that one of the etiological factors of pulmonary thromboembolism is a disorder of prostacyclin production in the endothelium, causing thrombosis by lupus anticoagulant.