Air-Containing Mediastinal Mass

Toms Franquet, MD, PhD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Location of air is key
- Retrocardiac mass with air or air-fluid level is characteristic of esophageal hiatus hernia
- Superior mediastinal air-fluid level often Zenker diverticulum
- Bronchogenic cyst usually subcarinal

Helpful Clues for Common Diagnoses

Hiatal Hernia
- ± air-fluid level
Esophageal Diverticulum
- Air-fluid level in mid-esophagus (traction) or in epiphrenic region (pulsion)
Zenker Diverticulum
- Air-fluid level in superior mediastinum (pharyngoesophageal junction)
- Complications: Aspiration pneumonia and bronchiolitis

Helpful Clues for Less Common Diagnoses

Achalasia
- Esophageal dilatation with air-fluid level
Esophageal Perforation
- Penetrating trauma (90%): Iatrogenic following endoscopic procedures, postsurgical and ingested foreign bodies (e.g., bones)
- Spontaneous: Boerhaave syndrome (esophageal rupture after emesis)
- Radiographic findings: Pneumomediastinum and subcutaneous emphysema in soft tissues of neck
- NECT: Gas collections centered around esophagus (90%)
Mediastinal Abscess
- Usually secondary to erosion from esophageal carcinoma
- Following cardiac or esophageal surgery

Helpful Clues for Rare Diagnoses

Bronchogenic Cyst
- Spontaneous cyst ruptures into airways, esophagus, pleural cavity, and pericardial cavity
  - Radiograph & CT: Large subcarinal cyst with air-fluid level (rupture)
Loculated Pneumomediastinum
- In neonates, air in mediastinum often loculates locally; tends not to dissect widely as in adults