What is the diagnostic and treatment approach for a patient presenting with perihilar fullness, possibly due to perihilar atelectasis, adenopathy, developing bronchopneumonia, venous congestion, or pulmonary arterial hypertension?

Diagnostic and Management Approach for Perihilar Fullness

Immediate Diagnostic Priorities

Begin with high-resolution CT chest with contrast to differentiate between the most critical diagnoses: pulmonary veno-occlusive disease (PVOD), pulmonary arterial hypertension (PAH), and infectious/inflammatory processes, as this single study provides the most actionable information for morbidity and mortality outcomes. 1

Critical CT Findings to Identify

For PVOD (highest mortality risk if mismanaged):

• Ground-glass opacities with centrilobular distribution (specificity 100% when combined with other findings) 1
• Interlobular septal thickening (significantly more frequent in PVOD, p<0.0001) 1
• Mediastinal adenopathy (significantly more frequent in PVOD, p<0.0001) 1
• Pleural effusions 1
• The combination of these three findings (ground-glass opacities, septal lines, adenopathy) has 100% specificity and 66% sensitivity for PVOD 1

For PAH without venous involvement:

• Central pulmonary artery dilatation (≥29 mm diameter) 1, 2
• Pulmonary artery to ascending aorta diameter ratio ≥1.0 1
• Peripheral vascular pruning (abrupt tapering of peripheral vessels) 1, 2
• Right ventricular enlargement 1
• Mosaic attenuation pattern from variable perfusion 1, 2

For infectious/inflammatory processes:

• Consolidation patterns suggesting bronchopneumonia 1
• Associated parenchymal abnormalities 1

For atelectasis:

• Crowded pulmonary vessels and air bronchograms 3
• Displacement of interlobar fissures 3

Mandatory Concurrent Investigations

Transthoracic Doppler Echocardiography

• Perform immediately to estimate pulmonary artery systolic pressure using tricuspid regurgitation velocity 1, 4
• Assess for left heart disease (valvular abnormalities, left atrial enlargement, left ventricular dysfunction) that could cause venous congestion 1, 4
• Evaluate right ventricular size and function 1, 4
• If tricuspid regurgitation velocity >2.8 m/s with additional echocardiographic signs of PH, proceed to right heart catheterization 1

Ventilation/Perfusion (V/Q) Scan

• Mandatory to exclude chronic thromboembolic pulmonary hypertension (CTEPH), which has surgical treatment options 1, 4
• Normal or low-probability V/Q scan excludes CTEPH with 90-100% sensitivity 1
• Segmental perfusion defects indicate CTEPH requiring pulmonary angiography 1

Baseline Laboratory and Functional Studies

• Complete blood count, comprehensive metabolic panel, thyroid function tests 1
• Brain natriuretic peptide (BNP) for prognostic information 1
• Serological testing: antinuclear antibodies, HIV, hepatitis panel (up to 40% of idiopathic PAH patients have positive ANA at low titers) 1
• Pulmonary function tests with diffusing capacity (DLCO) 4
• Arterial blood gas analysis 4
• ECG (prognostic value: P-wave amplitude ≥0.25 mV in lead II associated with 2.8-fold increased mortality risk) 1

Right Heart Catheterization Criteria

Proceed to right heart catheterization if:

• Echocardiography shows high probability of PH (tricuspid regurgitation velocity >2.8 m/s plus additional signs) 1, 4
• CT findings suggest PVOD or PAH 1
• Clinical presentation includes syncope or rapidly progressive symptoms 4

Hemodynamic definitions:

• Mean pulmonary artery pressure ≥25 mmHg confirms PH 1
• Pulmonary capillary wedge pressure (PCWP) ≤15 mmHg defines precapillary PH 1
• PCWP >15 mmHg indicates postcapillary PH from left heart disease 1
• Transpulmonary gradient >12 mmHg suggests intrinsic pulmonary vascular changes 1

Critical Management Decision Points

If PVOD is Confirmed or Suspected

IMMEDIATELY AVOID pulmonary vasodilators (sildenafil, bosentan, prostacyclins) as they worsen pulmonary edema and increase mortality 5

Management priorities:

1. Aggressive diuresis with loop diuretics and salt restriction 5
2. Urgent referral for lung transplantation evaluation (only curative therapy) 1, 5
3. Monitor closely for pulmonary edema development 5

If PAH Without Venous Involvement is Confirmed

Initiate PAH-specific therapy only after:

• Right heart catheterization confirms precapillary PH (PCWP ≤15 mmHg) 5
• PVOD has been excluded by CT findings 1
• Vasoreactivity testing performed at experienced center 1

Treatment options include:

• Phosphodiesterase-5 inhibitors (sildenafil 20 mg TID) 6
• Endothelin receptor antagonists (bosentan) 7
• Prostacyclin analogs 1

If Left Heart Disease/Venous Congestion is Identified

Primary management:

• Optimize treatment of underlying left heart disease 5
• Diuretics as primary therapy for volume overload 5
• Do NOT use PAH-specific therapy unless left heart disease is optimally treated AND PCWP is normal/minimally elevated AND transpulmonary gradient is significantly elevated 5

If Bronchopneumonia is Suspected

Obtain tissue diagnosis if:

• Patient has risk factors for malignancy (smoking history, age >66 years) 1
• Mediastinal adenopathy is present (up to 2 cm) 1

Biopsy approach (in order of preference):

1. Endoscopic/bronchoscopic biopsy (rating 8/9) 1
2. Percutaneous lung biopsy (rating 7/9) 1
3. Consider FDG-PET whole body imaging (rating 8/9) 1

If Atelectasis is Primary Finding

• Identify and address underlying obstructing lesion 3
• Bronchoscopy if resorption atelectasis suspected 3
• Chest physiotherapy and incentive spirometry for passive atelectasis 3

Common Pitfalls to Avoid

1. Never initiate pulmonary vasodilators before excluding PVOD with high-resolution CT - this can precipitate fatal pulmonary edema 1, 5
2. Do not rely on chest X-ray alone - perihilar fullness is nonspecific and most asymptomatic PAH patients have normal chest X-rays 1
3. Do not assume venous congestion equals left heart failure - PVOD presents with venous congestion but requires completely different management 1, 5
4. Do not use echocardiography-estimated pulmonary artery pressure as definitive diagnosis - right heart catheterization is mandatory for confirmation and treatment decisions 1, 4
5. Do not perform open lung biopsy in PAH patients - high risk with no diagnostic benefit 1

Referral Indications

Immediate referral to pulmonary hypertension center if:

• Syncope present (indicates severely compromised cardiac output) 4
• Rapidly progressive symptoms 4
• Echocardiographic signs of severe PH or severe right ventricular dysfunction 4
• PVOD suspected or confirmed (for transplant evaluation) 1, 5