Pulmonary tumor thrombotic microangiopathy caused by a gastric carcinoma expressing vascular endothelial growth factor and tissue factor.

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare clinicopathological entity causing severe pulmonary hypertension. Its histological features include widespread tumor emboli along with fibrocellular intimal proliferation and thrombus formation in the small arteries and arterioles of the lungs. The result is occlusion or stenosis of the pulmonary vasculature, but the detailed pathogenesis has yet to be clarified in spite of the serious clinical manifestations. Herein is described the case of a 62-year-old man with a gastric adenocarcinoma who died of sudden cardiopulmonary arrest. The autopsy revealed advanced cancer disease as well as findings of PTTM, which seemed to be the cause of his unexpected death. The carcinoma cells were immunohistochemically positive for vascular endothelial growth factor (VEGF) and also for tissue factor (TF). There is another report suggesting that TF might play an important role in the pathogenesis of PTTM. Also, VEGF has been reported to be involved in a variety of forms of pulmonary hypertension and to be upregulated by TF. These findings suggest that VEGF and TF may be involved in the pathogenesis of PTTM. The present PTTM case, in which the tumor cells demonstrate the coexpression of VEGF and TF, is important in facilitating understanding of the lethal disorder in the future.