Abstract
Primary mediastinal large B-cell lymphoma (PMBCL) is a specific subtype of diffuse large B-cell lymphoma (DLBCL), which occurs more frequently in young women. PMBCL is an uncommon kind of cancer. R-EPOCH is a common therapeutic regimen that is suitable for patients with PMBCL, and could get a relatively high complete remission rate. However, it may not be effective response in patients with relapsed PMBCL. Immunotherapy appears to be helpful in recent years. Therefore, in this case, a 31-year-old female patient with relapsed PMBCL. Progressive disease was identified after rechemotherapy and target therapy, complete remission can be achieved after switching to PD-1 inhibitor plus targeted therapy. These recurrence, progression, remission and follow-up are all displayed well on (18)F-FDG PET/CT. This case with consecutive imaging monitor illustrates that PD-1 inhibitor may be used as a first-line treatment for recurrent PMBCL. In addition, (18)F-FDG PET/CT is strongly recommended for monitoring PMBCL include baseline staging, interim response and follow-up study.