[Progress in the diagnose and treatment of pulmonary arterial thrombosis in situ]

In situ pulmonary arterial thrombosis (ISPAT) refers to the formation of new blood clots in the pulmonary arterial system in the absence of pre-existing clots in the peripheral venous system. With the emergence and prevalence of COVID-19, ISPAT has become an increasingly important cause of pulmonary arterial thrombosis (PAT) alongside thromboembolism. Several factors such as hypoxia, inflammation, endothelial dysfunction, and hypercoagulable state can lead to ISPAT, which is associated with a number of conditions such as thoracic trauma, partial lung resection, pulmonary infectious disease, pulmonary vasculitis, connective tissue diseases, severe pulmonary hypertension, radiation pneumonitis, and acute chest syndrome in sickle cell disease. It is important to differentiate between pulmonary thromboembolism (PTE) and ISPAT for proper disease management and prognosis. In this review, we summarized the characteristics of ISPAT under different disease conditions, the methods to distinguish ISPAT from PTE, and the best treatment strategies. We hoped that this review could improve clinicians' understanding of this independent disease and provide guidance for the refined treatment of patients with PAT.