ABSTRACT
Mediastinal masses may arise from any of the various types of tissue within the mediastinum. The mediastinum is divided into superior and inferior parts by a plane through the manubriosternal joint and the 5th dorsal vertebra, and into anterior, middle and posterior portions. Nodal enlargement may take place in any part of the mediastinum, but is particularly likely to be found anteriorly and in the middle part of the mediastinum. Acute infection of the mediastinum may follow perforation of the pharynx or oesophagus, inflammatory disease in the lungs or airways, an infected tracheostomy stoma, an infected cyst or haematoma, extension of nodal or bony infection, etc. The fibrosis usually starts at muscular aponeurotic insertions, and occurs mainly in the limb girdles of the shoulder and hips. Thymic masses seem particularly prone to haemorrhage, and patients with this may have severe dyspnoea, chest pain and a rapidly enlarging mediastinal mass.
