Primary Marginal Zone Lymphoma in the Posterior Mediastinum with Pleural Involvement

We herein report a case of primary marginal zone lymphoma (MZL) of the posterior mediastinum in an 84-year-old woman. Computed tomography of the chest showed a posterior mediastinal mass in the right thoracic paravertebral region with right pleural effusion. Pathological findings of a surgical biopsy from the posterior mediastinum, along with immunohistochemical and flow cytometric results, indicated MZL. The patient was treated with chemotherapy and radiation therapy for the mediastinal lesion and achieved complete remission. A relapse occurred 3 months after the initial treatment regimen. However, a second relapse has not occurred more than 2 years after second-line chemotherapy. This is the first case of MZL originating in the posterior mediastinum.