Platelet-derived growth factor-A and vascular endothelial growth factor-C contribute to the development of pulmonary tumor thrombotic microangiopathy in gastric cancer.

Pulmonary tumor thrombotic microangiopathy is a rare but lethal complication in cancer-bearing patients, particularly those with gastric cancer. It is characterized by cancer cell emboli with marked intimal proliferation. In the present study, we tried to elucidate the pathogenesis of pulmonary tumor thrombotic microangiopathy, notably angiogenic factors specific for cancer cells lodged in pulmonary arteries. An autopsy series of gastric cancer (51 cases) was reviewed for pulmonary tumor thrombotic microangiopathy and pulmonary tumor cell emboli without intimal proliferation. Pathological and immunohistochemical characteristics were compared between two groups. In eight cases in muscular pulmonary arteries, tumor thrombotic microangiopathy was noted, and in three cases pulmonary tumor emboli without intimal proliferation was noted. Histological features of pulmonary tumor thrombotic microangiopathy included small nests or single cancer cells accompanied by intimal proliferation, whereas in pulmonary tumor emboli large cell nests prevailed. By immunohistochemistry, in pulmonary tumor thrombotic microangiopathy, cancer cells expressed platelet-derived growth factor-A (7/8 cases) and vascular endothelial growth factor-C (8/8) more frequently than in pulmonary tumor emboli (0/3 and 1/3; P = 0.02 and P = 0.055, respectively). Expression of tissue factor, vascular endothelial growth factor-A and -D, osteopontin, fibroblast growth factor-2, and platelet-derived growth factor-B was similar in both groups. Platelet-derived growth factor-A and vascular endothelial growth factor-C might induce intimal proliferation in pulmonary arteries and contribute to the development of pulmonary tumor thrombotic microangiopathy.