Pneumothorax

Daniel J. Podberesky, MD

DIFFERENTIAL DIAGNOSIS

Common

Pulmonary Hypoplasia
Surfactant Deficiency Disease
Meconium Aspiration Syndrome
Pulmonary Interstitial Emphysema
Asthma
Cystic Fibrosis, Lung
Iatrogenic
Spontaneous
Trauma
Skin Fold (Mimic)

Less Common

Langerhans Cell Histiocytosis
Tuberous Sclerosis Complex
Ruptured Bulla/Blebs

Rare but Important

Metastatic Neoplasm
Infection
Marfan Syndrome
Ehlers-Danlos Syndrome

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

History is extremely helpful in determining possible source of pneumothorax
- Is there history of trauma? asthma? recent instrumentation?
Appearance of pneumothorax depends on position of patient and amount of pleural gas
- In supine patient, air collects anteromedially
  - Sharp, well-delineated cardiac and mediastinal borders
- In upright patient, air collects laterally and apically
  - Radiolucent space lacking pulmonary vascular markings
  - White pleural line visible
Size of pneumothorax difficult to accurately estimate on chest x-ray
Signs of tension pneumothorax
- Depressed/inverted hemidiaphragm
- Contralateral shift of mediastinum
- Expansion of spaces between ribs
Expiratory, decubitus, and cross-table lateral views may all aid in diagnosis in equivocal cases
Skin folds and pneumomediastinum can mimic pneumothorax

Helpful Clues for Common Diagnoses

Pulmonary Hypoplasia
- Potter syndrome
  - Oligohydramnios related to fetal urinary system problems
  - Resultant pulmonary aplasia and typical abnormal facies
- Pneumothorax may result from progressive air leaks &/or mechanical ventilation
Surfactant Deficiency Disease
- Premature neonates
- Reticulogranular opacities
- Air leak from alveolar rupture can lead to pneumothorax
Meconium Aspiration Syndrome
- History of meconium-stained amniotic fluid helpful
- Coarse interstitial and patchy opacities
- Hyperinflation
- Pneumothorax may result from air-trapping and alveolar rupture
Pulmonary Interstitial Emphysema
- Premature neonates
- Barotrauma from mechanical ventilation
- Reticular and cystic opacities
- Alveolar rupture results in pneumothorax
Asthma
- Airway narrowing and mucous plugging leads to air-trapping and alveolar rupture
- History of asthma exacerbation helpful
- Hyperinflated lungs
Cystic Fibrosis, Lung
- Chronic lung disease can lead to airway obstruction and alveolar rupture
- Superimposed infection increases pneumothorax risk
- Pneumothorax indicates poor prognosis
- Bronchiectasis, bronchial wall thickening, mucus plugging, hyperinflation, prominent hila
Iatrogenic
- Mechanical ventilation
- Instrumentation, such as central line placement or thoracentesis
- Postoperative patients
- History helpful
Spontaneous
- Diagnosis of exclusion
- No distinguishing radiologic features
Trauma
- Pneumothorax may result from acute blunt or penetrating trauma
- May also result from rupture of pneumatocele from old trauma
- Motor vehicle crashes, falls, sports injuries
- Other signs of trauma
  - Fractures
  - Pulmonary contusions
  - Mediastinal injuries
  - Pleural effusions
Skin Fold (Mimic)
- Frequently seen in neonates in NICU
- Can be difficult to differentiate from pneumothorax
  - Linear interface with Mach line
  - No white pleural line
- Consider decubitus or cross-table lateral views in equivocal cases

Helpful Clues for Less Common Diagnoses

Langerhans Cell Histiocytosis
- Small pulmonary nodules and parenchymal lung cysts
- Apical reticulonodular pattern
- Lung cysts may rupture and result in pneumothorax
Tuberous Sclerosis Complex
- Lymphangioleiomyomatosis
- Small parenchymal cysts
- Chylous pleural effusion
- Pneumothorax in ˜ 70%
Ruptured Bulla/Blebs
- Small pleural blebs and parenchymal bulla may spontaneously rupture and lead to pneumothorax
- CT can be very helpful in these cases

Helpful Clues for Rare Diagnoses

Metastatic Neoplasm
- Pneumothorax may occur in presence of metastases, especially when present on pleural surface
- Seen in children with osteosarcoma and Wilms tumor
Infection
- Any infection that causes alveolar destruction can lead to pneumothorax
- Particularly seen with tuberculosis and Pneumocystis infection
Marfan Syndrome
- Autosomal dominant connective tissue disorder
- At risk for spontaneous pneumothorax
- Look for associated findings
  - Aortic aneurysms
  - Kyphoscoliosis
  - Arachnodactyly
Ehlers-Danlos Syndrome
- Connective tissue disorder
- At risk for spontaneous pneumothorax

Image Gallery

Frontal radiograph in this neonate with Potter syndrome shows a moderate right pneumothorax

. Note the shift of cardiomediastinal silhouette to the left

, evidence of a tension component.

Frontal radiograph shows a large right-sided tension pneumothorax

in this premature neonate with surfactant deficient disease. Note the granular opacities throughout the lungs.

(Left) Frontal radiograph shows bilateral pneumothoraces in this neonate with meconium aspiration. Note the bilateral, coarse, interstitial lung opacities. The left pneumothorax is loculated