Primary mediastinal large B-cell lymphoma accounts approximately 5% of large B-cell lymphoma, which are usually disseminated or present in the abdomen. There appears to be a younger age of diagnosis (30s) and female predilection (F:M 3:2), when compared to other large-cell lymphoma, which usually present in the 50s and have a male predilection (M:F 2:1).
Unfortunately from an imaging point of view, these demographics are similar to those of nodular sclerosing Hodgkin lymphoma, which is a common cause of a primarily mediastinal lymphoma.
There Clinical presentation is usually due to the mass effect of the typically large anterior mediastinal mass. SVC compression resulting in SVC syndrome is relatively common, present in up to 35% of cases.
The vast majority of patients have an anterior mediastinal mass. Middle and posterior mediastinal involvement, either in isolation or contiguously with the anterior mediastinal component is uncommon.
Chest radiography demonstrates a soft tissue anterior mediastinal mass.
CT of the chest usually shows:
* soft tissue attenuating mass
* usually large at diagnosis ~10cm diameter
* mass effect common
- bowing and compression of trachea
- SVC obstruction : up to 35% cases
* calcification pre-treatment is uncommon, but recognised
* chest wall invasion may occur
* pleural effusion(s) / pericardial effusion
- seen in up to a third of cases
- pleural effusion may be associated with poor outcome