# PD-1 inhibitor in the treatment of relapsed primary mediastinal large B-cell lymphoma follow up by 18F-FDG PET/CT: A case report and literature review

## TL;DR

A 31-year-old woman with relapsed primary mediastinal large B-cell lymphoma achieved remission using a PD-1 inhibitor, monitored effectively with 18F-FDG PET/CT scans.

## Contribution

This case report highlights PD-1 inhibitors as a potential first-line treatment for recurrent PMBCL, supported by detailed PET/CT monitoring.

## Key findings

- PD-1 inhibitor plus targeted therapy achieved complete remission in a patient with relapsed PMBCL.
- 18F-FDG PET/CT effectively monitored disease progression and response to treatment.
- Progressive disease after rechemotherapy and targeted therapy was reversed with PD-1 inhibitor therapy.

## 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 18F-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, 18F-FDG PET/CT is strongly recommended for monitoring PMBCL include baseline staging, interim response and follow-up study.