Spontaneous Regression of Epstein-Barr Virus-Positive Primary Diffuse Large Cell B-Cell Lymphoma of the Urinary Bladder After the Cessation of Enzalutamide

Abstract

� Primary lymphoma of the urinary bladder is a rare condition. � The development of Epstein-Barr virus (EBV)-positive lymphoma in immunosuppressed patients has been characterized; however, no case has been reported of EBV-positive primary lymphoma of the urinary bladder occurring in patients undergoing treatment of prostate cancer. � Our patient had been treated with enzalutamide after maximum androgen blockage therapy, followed by docetaxel chemotherapy. � Eleven years after the initial diagnosis, a bladder tumor was detected by magnetic resonance imaging (MRI) during a routine physical examination. � The tumor was suspected to be a grade higher than T2; however, no recurrence of prostate cancer was noted. � MRI performed again after stopping enzalutamide therapy and before surgery revealed that the bladder tumor had spontaneously decreased to stage T1. � We performed transurethral resection of the bladder tumor; histopathologic examination showed it was EBV-positive diffuse large B-cell lymphoma (DLBCL), which was confirmed by in situ hybridization. � To our knowledge, this is the first case of EBV-positive primary DLBCL of the urinary bladder that might have been induced by enzalutamide. � This case emphasizes the importance of the unknown effects of enzalutamide on the immune system.