The present study consists of a retrospective multicentric collection of all consecutive patients with PMBCL diagnosed over the time period considered (13 years, from 2007 to 2019 inclusive).

The study was initially set up as a spontaneous, non-profit study, with ARNAS Garibaldi of Catania (PI Dr Ugo Consoli) as the proposer. Subsequently, the project was expanded to include additional centres belonging to the Italian Lymphoma Foundation, which became the promoter in collaboration with ARNAS Garibaldi of Catania. The information collected is aimed at verifying the application in a "real world" context of the PMBCL diagnosis and therapy protocols suggested in the guidelines and at checking whether they produce results in line with those expected.

The therapies considered for the I line of treatment are those described in the literature for the pathology under consideration:

• R-CHOP14; R-CHOP21 and R-CHOP like, (R-CHOP: rituximab - cyclophosphamide, doxorubicin, vincristine, prednisone)
• R-VACOPB, R-MACOPB and R-VACOPB like, MACOPB like, (R-VACOP-B: Rituximab - etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin. R-MACOP-B: Rituximab - methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin)
• R-DA-EPOCH ed R-EPOCH like (DA-R- EPOCH: Dose Adjusted - Rituximab - Etoposide, Prednisone, Vincristine, Cyclophosphamide, Doxorubicin)

Inclusion Criteria:

• All consecutive patients treated in the centre during the period considered
• Age>=18 years
• Histological diagnosis of PMBCL
• Signature of "Informed Consent" to participate in the study (if applicable)
• Treatment according to local practice
• Diagnosis between 01 January 2007 and 31 December 2019

Exclusion Criteria:

- The exclusion criteria, being an observational study, are focused and limited to excluding cases with a non-compliant histological diagnosis.

Patients newly diagnosed with PMBCL between 01 January 2007 and 31 December 2019 attending participating centres.