May Be Caused by

 Common

Blastomycosis

Carcinoid

Coccidioidomycosis

Histoplasmosis

Infectious hilar lymphadenopathy

Leukemia

Lymphoma

Metastasis

Primary tuberculosis

Small cell lung carcinoma

Sporotrichosis

Squamous cell lung carcinoma

 Uncommon

Arteriovenous malformation

Blalock-Taussig shunt

Bronchiolo-alveolar carcinoma

Central pulmonary artery coarctation

Congenitally absent contralateral pulmonary artery

Contralateral pulmonary embolism

Cystic fibrosis

Hypoplastic contralateral pulmonary artery

Main pulmonary artery thromboembolus

Neoplasm

Pericardial defect

Potts-Smith shunt

Pulmonary artery aneurysm

Sarcoidosis

Swyer-James syndrome

Waterston-Cooley shunt