The differential of enlarged pulmonary trunk / main pulmonary artery on chest radiography includes:

* normal
o may appear prominent in young patients especially women

* projectional
o rotation
o lordotic view

* rotation of heart
o pectus excavatum
o left lower lobe collapse

* pulmonary arterial hypertension (PAH)

* pulmonary embolism

* post stenotic dilatation
o pulmonary valve stenosis
o pulmonary artery coarctation

* increased pulmonary blood flow
o left to right shunt
+ atrial septal defect (ASD)
+ ventricular septal defect (VSD)
+ patent ductus arteriosus (PDA)
o total anomalous pulmonary venous return (TAPVR)
o pregnancy
o high output cardiac failure
+ thyrotoxicosis
+ anaemia

* Marfan syndrome

* mimics
o enlarged left atrial appendage
o left hilar / mediastinal mass

Enlarged pulmonary artery

Normal pulmonary artery

Pulmonary valve stenosis

Pulmonary arterial hypertension

Article Author : Dr Frank Gaillard, Radiopaedia

References

* 1. Differential diagnosis in chest x-rays. Francis A. Burgener, Martti Kormano. Stuttgart; Thieme, 1997. ISBN:0865776776
* 2. Reeder and Felson's gamuts in radiology. Maurice M. Reeder; with MRI gamuts by William G. Bradley, Jr., and ultrasound gamuts by Christopher R. Merritt and input from a distinguished 20-member subspecialty editorial board. New York : Springer, c2003. ISBN:0387955887