Diffuse large B-cell lymphoma of the mediastinum (PMBL), a specific subtype of diffuse large B-cell lymphoma (DLBCL), is distinguished from the non-specific type of diffuse large B-cell lymphoma by its epidemiologic, clinical, and biological behavior and has a relatively good prognosis. It is similar to nodular sclerosing Hodgkin lymphoma (NSHL), which occurs in the mediastinum and presents as an anterior mediastinal mass that may invade local structures. Studies at the genetic level suggest that PMBL and NSHL share some of the same genetic abnormalities. Because of the small number of cases, mostly retrospective studies and unclear diagnostic criteria, there is still controversy in the treatment. As far as the available studies suggest, chemotherapy prefers higher dose intensity regimens, with Dose-adjusted EPOCH-R being the most respected. One of the major controversies regarding treatment is the issue of consolidation radiotherapy. Some early studies suggest that consolidation radiotherapy has an important place in the treatment of PMBL. In a pre-PET era study, the administration of consolidation radiotherapy to the mediastinum after chemotherapy with the MACOP-B regimen showed gallium activity in 66% of pre-treatment cases, which dropped to 19% after treatment, which was one of the early studies supporting consolidation radiotherapy. Now that we have come to the era of melphalan, the importance of melphalan in PMBL cannot be denied, despite the lack of prospective studies. Has the improved efficacy brought by melovar diminished the status of consolidation radiotherapy? However, in a recent prospective single-arm study by NCI, a Dose-adjusted EPOCH-R regimen was used without consolidation radiotherapy, and the 5-year EFS and OS reached 93% and 97%, so it seems that consolidation radiotherapy after high-intensity chemotherapy combined with Meroval is no longer necessary. However, this needs to be confirmed in a prospective controlled study, and a prospective study currently underway comparing the outcome of PET-negative patients treated with and without consolidation radiotherapy after immunotherapy may eventually give us a satisfactory answer to the question of chemotherapy regimen and whether or not to consolidate radiotherapy because of the heterogeneity of the study’s chemotherapy regimen.