Pulmonary Arterial Enlargement
Sudhakar Pipavath, MD
DIFFERENTIAL DIAGNOSIS
Common
Pulmonary Arterial Hypertension (PAH)
Pulmonic Valvular Stenosis (Post-Stenotic Dilatation)
Atrial Septal Defect (ASD)
Less Common
Takayasu Arteritis
Pulmonary Artery Aneurysm
Rare but Important
Mitral Stenosis or Regurgitation
Pulmonary Venoocclusive Disease
Pulmonary Capillary Hemangiomatosis
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Radiographic features of PAH
Disproportionate enlargement of central pulmonary arteries (PA)
Does not appear multilobular like hilar adenopathy
Right ventricular enlargement, especially with intracardiac shunt and right heart failure
CT features of PAH
Increased main pulmonary artery (PA) measurement above 3 cm
Main PA to ascending thoracic aortic ratio of ≥ 1
Helpful Clues for Common Diagnoses
Pulmonary Arterial Hypertension (PAH)
Enlargement of central PA and peripheral pruning
Pulmonic Valvular Stenosis (Post-Stenotic Dilatation)
Disproportionate enlargement of main and left pulmonary arteries
Right ventricle enlargement
Atrial Septal Defect (ASD)
Increased pulmonary vascular flow
Cardiomegaly: Enlarged right ventricle and right atrium
Helpful Clues for Less Common Diagnoses
Takayasu Arteritis
Pulmonary artery wall thickening
Aneurysmal dilatation
Pulmonary Artery Aneurysm
Focal dilatation in continuation with pulmonary artery
Helpful Clues for Rare Diagnoses
Mitral Stenosis or Regurgitation
Cardiomegaly
Left atrial enlargement
Pulmonary Venoocclusive Disease
Interlobular septal thickening
Ground-glass opacities but without centrilobular distribution
Pulmonary Capillary Hemangiomatosis
Poorly defined ground-glass nodules in centrilobular or random distribution
Ground-glass represents capillary proliferation beyond resolution of imaging technique
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