Mediastinum

This patient has a well circumscribed mass in the posterior mediastinum. The valve of the lateral view is well depicted in this case; on the frontal radiograph there is no way to localize the lesion. The differential diagnosis for a posterior mediastinal mass includes:

• lymphoma
• lung cancer
• aortic aneurysm or other vascular abnormality
• abscess
• hematoma
• neurogenic tumour (e.g. neurofibroma, schwannoma)
• multiple myeloma
• pheochromocytoma
• neurenteric cyst, thoracic duct cyst
• lateral meningocele
• Bochdalek hernia
• extramedullary hematopoiesis

This mass proved to be a neurofibroma.

This patient has a large mass in the middle mediastinum. The differential diagnosis for such a mass includes:

• lymphoma or other lymphadenopathy
• lung cancer
• aortic aneurysm or other vascular abnormality
• abscess
• hematoma
• esophageal carcinoma, esophageal duplication cyst
• metastatic disease
• hiatus hernia
• bronchogenic cyst

This elderly patient complained of gastroesophageal reflux symptoms. This clinical history, plus the presence of an air-fluid level within the mass suggests a hiatus hernia.

PA and lateral chest radiographs of a hiatal hernia. Left: PA chest view demonstrates a retrocardiac lucency with well defined lateral margins. Right: Lateral radiograph shows a large hiatal hernia in the middle mediastinum. Hiatal hernia is the most common radiographic abnormality of the middle mediastinum.

Radiologists divide the mediastinum into 3 compartments. The most popular classification is Felson’s division of the thorax into the following 3 compartments:

• Anterior: Everything from the sternum to the posterior aspect of the heart and great vessels.
• Middle: The compartment posterior to the heart and great vessels, to a line drawn 1 cm posterior to the anterior edge of the thoracic vertebrae.
• Posterior: The space behind the posterior limit of the middle mediastinum.

This approach is very useful in classifying mediastinal masses (please refer to Diagnostic Medical Imaging Chapter or to examples of mediastinal masses to follow).

There is a large mass in this patient’s anterior mediastinum. The differential diagnosis for such a mass includes:

• lymphomA
• lung cancer
• aortic aneurysm or other vascular abnormality
• abscess
• hematoma
• teratoma, thyroid, parathyroid or thymic neoplasm
• thymic or pericardial cyst, epicardial fat pad
• foramen or Morgani hernia

In this case, the mass is accompanied by significant hilar and paratracheal lymphadenopathy. The patient is young and complains of fevers and night sweats. He was diagnosed with Hodgkin’s Lymphoma.