Posterior Mediastinal Mass

The middle mediastinal region includes the following:

•Bounded anteriorly by the pericardium and vertical portion of diaphragm, laterally by the mediastinal pleura, and posteriorly by the thoracic vertebrae. It contains the esophagus, descending aorta, azygous and hemiazygous veins, thoracic duct, autonomic nerves, fat, and lymph nodes.

There are a number of causes of posterior mediastinal masses. You can use the mnemonic NECO to help you remember the overall differential.

N – Neurogenic

•Nerve root tumors

•Ganglion tumors

•Paragangliomas

•Lateral meningocele

E – Esophageal

•Esophageal carcinoma

•Benign esophageal neoplasm

•Hiatal hernia

•Pulsion diverticuli

•Achalasia

•Esophageal varices

C – Cysts

•Duplication cysts

•Enteric cysts

•Neurenteric cysts

•Bronchogenic cysts

O – Others

•Extralobar sequestration – 2/3 in lower lobes

•Inflammation

•Vascular lesions

•Trauma

•Abdominal origin posterior masses, e.g., Bochdalek hernia

Case 6.2

Figure 6.2 show CXRs demonstrating a partially circumscribed mass

The Fig. 6.2c is a CT of the same patient showing an irregular mass emanating from the esophagus, consistent with an esophageal stromal tumor (confirmed by surgery).