Tumors of the pulmonary vasculature

The rare primary tumors arising from the pulmonary vasculature are mostly sarcomas of the main pulmonary arteries and veins. Sarcomas arising in the pulmonary arterial intima are far more prevalent than those arising in the venous intima or those arising in the muscular media of pulmonary arteries and veins. Clinically, intimal sarcomas of pulmonary arteries are often indistinguishable from pulmonary chronic thromboembolic diseases, which causes delayed diagnosis and fatal outcome. Most sarcomas of the pulmonary veins are mural sarcomas, which tend to follow a somewhat less dismal clinical course than intimal sarcomas of the pulmonary artery. Pulmonary capillary hemangiomatosis is a rare disease of unknown etiology that shows the histopathologic features of a locally infiltrative, low-grade neoplasm despite the high mortality rate due to the accompanying severe pulmonary hypertension. Secondary tumors in the pulmonary vasculature may masquerade as primary vascular tumors or as primary/idiopathic pulmonary hypertension. Thrombotic microangiopathy and intimal carcinomatosis have been described as the distinct patterns seen in the secondary arterial involvement. Pulmonary venous tumor thrombosis may result in pulmonary infarctions or even systemic infarctions by way of left atrial involvement with subsequent systemic tumor embolism.