Bevacizumab combined with pemetrexed successfully treated lung adenocarcinoma complicated with pulmonary tumor thrombotic microangiopathy: a case report and literature review

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare but severe pulmonary complication of malignant tumors. It is characterized by the presence of multiple microscopic tumor emboli attached to the endothelium of small pulmonary arteries and induces fibrointimal proliferation and the activation of coagulation. The main clinical manifestations of PTTM are dyspnea, dry cough, hypoxemia, pulmonary hypertension, right heart failure, thrombocytopenia, and disseminated intravascular coagulation (DIC). Chest computed tomography (CT) shows no distinctive findings, and PTTM is often unrecognized and universally underdiagnosed, with an appalling prognosis. An antemortem diagnosis of PTTM is also difficult due to a lack of specific clinical and imaging features. Moreover, there is presently no therapeutic management and the illness rapidly progresses to death. Early identification and timely and effective use of oncotherapy can help to alleviate symptoms and improve prognosis. According to recent reports, targeting angiogenesis factors including platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) have marginally improved survival. In this article, we report the case of a patient with advanced lung adenocarcinoma complicated with PTTM and DIC. A combined therapeutic regimen of bevacizumab with pemetrexed successfully improved chest CT findings, respiratory symptoms, DIC, and short-term outcomes. Anti-angiogenesis drugs modify the pulmonary vascular structure, and rapidly improve the lung tumor microenvironment. And therefore, it may be a potentially effective drug for the treatment of PTTM.