Bilateral Hilar Mass

Christopher M. Walker, MD

DIFFERENTIAL DIAGNOSIS

Common

Sarcoidosis
Pulmonary Arterial Enlargement

Less Common

Lymphadenopathy Associated with Infections
Lymphoma

Rare but Important

Silicosis/Coal Worker’s Pneumoconiosis
Berylliosis
Lymphadenopathy Secondary to Metastatic Disease
Angioimmunoblastic Lymphadenopathy
Amyloidosis

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Bilateral hilar mass usually secondary to pulmonary artery or hilar lymph node enlargement
- Lobulated contour in lymph node enlargement
- Smooth contour in pulmonary arterial enlargement

Helpful Clues for Common Diagnoses

Sarcoidosis
- Systemic disease of unknown etiology
- Common in African-American females of childbearing age
- Most patients present with thoracic lymph node enlargement
- 50% have associated lung disease
- Hilar lymph node enlargement in ≥ 80%
  - Lobulated and symmetric
  - ± calcification
- 1, 2, 3 sign (Garland triad)
  - Right paratracheal (1), right hilar (2), and left hilar (3) nodal enlargement
- CT findings
  - Symmetric hilar and mediastinal nodal disease
  - 25-50% of nodes show calcification
  - Eggshell calcification
  - Lung nodules (noncaseating granulomas) along fissures, subpleural lung, and bronchovascular bundles
  - Upper lung predominant
Pulmonary Arterial Enlargement
- CT angiogram diagnostic
- Etiologies include
  - Pulmonary arterial hypertension, primary and secondary causes
  - Left-to-right shunts
  - Idiopathic with no associated pulmonary hypertension
- Most common cause is pulmonary arterial hypertension
- Radiographic and CT findings
  - Dilatation of central pulmonary arteries with pruning and tapering of distal vessels
  - Main pulmonary artery ≥ 29 mm
  - Main pulmonary artery ≥ size of ascending aorta
  - Calcification of pulmonary arterial wall seen with irreversible longstanding disease
  - ± mosaic perfusion due to associated small vessel disease
- Examples of left-to-right shunts
  - Atrial septal defect
  - Ventricular septal defect
  - Partial anomalous pulmonary venous return
  - Patent ductus arteriosus
- Eisenmenger syndrome
  - Reversal of left-to-right shunt caused by elevated pulmonary arterial pressure exceeding systemic pressure

Helpful Clues for Less Common Diagnoses

Lymphadenopathy Associated with Infections
- Most commonly seen with Histoplasma or Coccidioides infections
- Primary M. tuberculosis usually unilateral disease
- ± miliary lung nodules
- ± lung consolidation
- Low-attenuation lymph nodes common with endemic fungi
- Elevated blood titers helpful in diagnosis
Lymphoma
- Hodgkin disease
  - Nearly all patients have superior mediastinal nodal involvement
  - 25-35% have hilar disease
  - Calcification occurs post radiotherapy
  - 20% of nodes appear necrotic
  - 10% of patients have lung involvement
- Non-Hodgkin lymphoma
  - Hilar nodal disease less common than in Hodgkin disease

Helpful Clues for Rare Diagnoses

Silicosis/Coal Worker’s Pneumoconiosis
- Hilar and mediastinal nodal enlargement in 30-40%
- Eggshell calcification of lymph nodes in 5%
- Upper lobe predominant centrilobular or perilymphatic lung nodules
- ± calcification of lung nodules
- Progressive massive fibrosis
  - Upper lobe conglomeration of nodules into large masses with volume loss and upward hilar retraction
  - Cavitation may indicate Tuberculosis superinfection
Berylliosis
- Occupational lung disease
- Ceramic industry, aerospace industry, nuclear power production
- Identical radiographic appearance to sarcoidosis
  - Symmetric hilar and mediastinal lymphadenopathy
  - ± lymph node calcification
  - Small nodules along fissures, subpleural lung, and bronchovascular bundles (perilymphatic distribution)
- Positive BAL or serum beryllium lymphocyte proliferation test
- Symptoms
  - Dyspnea most common
  - ± cough, chest pain, and fatigue
Lymphadenopathy Secondary to Metastatic Disease
- Unilateral hilar metastases are more common
- Lymph nodes usually round and well defined
- ± central low density
- Most common cause is bronchogenic carcinoma
  - Presence of contralateral hilar lymph node metastases indicates N3 disease (unresectable)
Angioimmunoblastic Lymphadenopathy
- Erroneously called a systemic disease associated with immunodeficiency
- Now accepted as peripheral T-cell lymphoma (non-Hodgkin lymphoma)
- Mediastinal and hilar nodal enlargement ± lung disease
- Pleural effusions in 40%
Amyloidosis
- Hilar enlargement secondary to
  - Thickening of central airways from amyloid deposition
  - Lymph node enlargement
- Perilymphatic lung nodules
- ± calcification in nodules and lymph nodes
- Cardiac involvement leads to restrictive cardiomyopathy

Image Gallery

Axial NECT shows symmetric calcified hilar

and subcarinal

lymph nodes.

Frontal radiograph shows enlarged hili

and right paratracheal lymph nodes

with eggshell calcification.

(Left) Axial NECT shows typical mildly calcified symmetric hilar

and subcarinal

lymph nodes. Characteristic perilymphatic lung nodules are shown in the next image. (Right) Coronal NECT shows typical perilymphatic nodules in sarcoidosis. Note beading along the major fissure