A non-profit study designed with the aim of analysing the phenotype and molecular characteristics (central review) and evaluating prospectively the role of PET-scans in the management of primary mediastinal lymphoma treated with conventional approaches.

Inclusion Criteria:

• Primary mediastinal diffuse large B-cell lymphoma, CD20 positive. Patients must have histological confirmation of the diagnosis, and in addition have a dominant mass within the anterior mediastinum.
• No prior treatment of lymphoma. Patients may have received corticosteroids for up to 1 week for the relief of local compressive symptoms.
• Any stage of disease.
• Age at least 18 years.
• Fit to receive chemotherapy with curative intent.
• Able and willing to give informed consent, and to undergo staging including PET scanning
• Willingness to comply with an appropriate contraceptive method in women of childbearing potential or men.

Exclusion Criteria:

• Evidence of clinically significant cardiac disease, as defined by history of symptomatic ventricular arrhythmias, congestive heart failure or myocardial infarction within 12 months before study entry. Cardiac compromise due to local extension of lymphoma will not be an exclusion criterion in the absence of other cardiac disease.
• Impairment of bone marrow function (WBC <3.0x109/L, ANC <1.5x109/L, PLT <100x109/L), unless due to involvement by lymphoma.
• Major impairment of renal function (serum creatinine >2x upper normal) or liver function (ASAT/ALAT >2,5 upper normal, total bilirubin >2,5x upper normal), unless due to lymphoma involvement.
• Known HIV infection. Patients will not be tested routinely.
• Pregnant or lactating women.
• Any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial

patient must have histological confirmation of the diagnodis of primary mediastinal diffuse large B cell lymphoma and have a dominant mass within the anterior mediastinum