Tumors of the pulmonary vasculature.

Most primary tumors of the pulmonary vasculature are sarcomas arising in the main pulmonary arteries and veins with high mortality rates. Pulmonary artery sarcoma is far more prevalent than its venous counterpart, though both are rare. Pulmonary capillary hemangiomatosis is a rare low-grade tumor or tumor-like lesion of the pulmonary capillaries that causes severe pulmonary hypertension. Secondary involvement of pulmonary vasculature by malignant tumors may rarely mimic a primary vascular tumor or clinically present as unexplained pulmonary hypertension associated with thrombotic microangiopathy.