Large amounts of normal fat; smooth symmetrical mediastinal widening without mass effect

Associated with Cushing syndrome, steroid treatment, and obesity

Normal: Generalized thymic enlargement (< 5 years old)

Hyperplasia: Immunologic rebound phenomenon

Most common cause of tracheal deviation; anterosuperior or posterosuperior mediastinal mass

Non-Hodgkin lymphoma: Bulky, bilaterally asymmetrical, mediastinal-hilar adenopathy

Hodgkin lymphoma: Due to nodal aggregation; rounded or bulky soft tissue masses; prevascular and paratracheal nodes

Teratoma: Multiple tissue densities

Nonseminomatous GCT: Large, irregular-shaped anterior mediastinal mass; pleural effusions and pulmonary metastasis common

Unilocular or multilocular (30%); may insinuate around normal structures

Low signal intensity on T1WI; high signal intensity on T2WI

Compensatory phenomenon due to inadequate production or excessive destruction of blood cells, e.g., sickle cell disease

Paravertebral masses: Single or multiple; unilateral or bilateral

Rare malignant mediastinal tumor