Primary mediastinal large B-cell lymphoma is an important differential among mediastinal tumours.

The study involved 51 patients with histopathologically verified diagnoses of primary mediastinal large B-cell lymphoma (PMBL). Clinically they presented as the anterior mediastinal tumours, frequently with the superior vena cava syndrome (21 patients) and usually (in 42 out of 51) without involvement of other locations. Morphologically the tumours were very pleomorphic. Histopathologically they were composed of germinal center cells, clear cells or polymorphic cells of various size and shape. However, there were also PMBLs composed of cells resembling Reed-Sternberg and Hodgkin cells and small cells. Various types of stromal sclerosis were evident in most biopsies. Due to lymphoma patterns mimicking other tumours with primary or secondary mediastinal location it was necessary to use a panel of immunocytochemical stains. CD20 staining proved to be indispensable for distinguishing PMBL. The patients were treated with CHOP or MEVA (V-VIII courses) followed by radiotherapy of the mediastinum (3600-4200cGy/t). Complete remission was obtained in 21 patients with overall survival ranging from 36 to 99 months. A total of 24 patients are alive, 3 of them live with persisting disease. One patients was lost to follow up, 26 died despite the treatment due to persistence of mediastinal tumour or dissemination to distant organs.