May Be Caused by

 Common

Arteriovenous malformation

Granulomatous lung disease

Neoplasm of lung

Obstruction of pulmonary artery

Obstruction of pulmonary vein

Pulmonary embolism

Pulmonary varix

Pulmonary vein thrombus

 Uncommon

Anomalous insertion of pulmonary vein into left atrium

Bronchial artery dilatation

Cirsoid aneurysm

Coarctation of pulmonary artery

Mycotic aneurysm

Osler-Weber-Rendu syndrome

Partial anomalous pulmonary venous return

Polyarteritis nodosa

Portal hypertension

Pulmonary artery aneurysm

Pulmonary artery arising from aorta

Pulmonary artery stenosis with post-stenotic dilatation

Pulmonary sequestration

Pulmonary veno-occlusive disease

Scimitar syndrome

Systemic artery-pulmonary artery shunt

Takayasu arteritis

Telangiectasia

Tetralogy of Fallot

Tetralogy of Fallot with absent pulmonary valve