Pulmonary Vein Thrombosis (PVT) is rare, often underdiagnosed, yet potentially life-threatening [1].
Its causes can be divided into postoperative factors—such as lobectomy, lung transplantation, radiofrequency catheter ablation, and arteriovenous malformation—and non-postoperative factors, including primary or secondary lung cancer, metastases, chest trauma, hiatal hernia, pulmonary aspergillosis, and omalizumab therapy [2,3]. Some cases remain idiopathic, often in the context of hemoglobinopathies [1-3].

Pathophysiology
After surgery, PVT may develop due to turbulent blood flow or stasis in the residual vein stump [2]. In cancer-related cases, the mechanism is less clear but may involve tumor extension into the vein, endothelial injury from tumor invasion, or a hypercoagulable state [1]. Increased pulmonary venous pressure can lead to compensatory pulmonary arterial vasoconstriction, raising pulmonary artery pressure and causing right ventricular expansion [3].

Clinical presentation
Symptoms are non-specific—dyspnea, cough, and hemoptysis—often mimicking pulmonary embolism [1,3]. Hemodynamic signs are also non-specific, and the condition may be asymptomatic, especially in older patients [1,2].

Diagnosis
Chest CT angiography is the preferred imaging method, typically showing a well-defined, hypodense endoluminal thrombus in a pulmonary vein [1,3], outlined by contrast but not enhancing after injection [1].
Transthoracic or transesophageal echocardiography can visualize atrial thrombi [3] and is particularly useful for postoperative follow-up [3].

MRI helps distinguish bland from tumor thrombi: bland thrombi show high T1/T2 signal in the acute phase and low T2 (“flow void”) in chronic stages, without enhancement. Tumor thrombi may show vessel wall invasion, restricted diffusion, and post-contrast enhancement [1].

Complications
Delayed diagnosis or treatment can lead to severe outcomes: pulmonary hypertension with shock, pulmonary infarction, edema, fibrosis, massive hemoptysis, renal infarction, or ischemic stroke from embolization [1, 3].

Management
There is no clear consensus on treatment [1, 3]. In most cases, anticoagulation is given unless bleeding is present.
For postoperative thrombi, antibiotics plus anticoagulation are recommended, with thrombectomy in severe cases; spontaneous resolution is possible.
For tumor thrombi, anticoagulation is combined with tumor-specific therapy, and surgical resection may be considered if the tumor is operable [1].