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.