Membranous nephropathy and thrombotic microangiopathy secondary to metastatic prostate cancer after Iodine-125 prostate brachytherapy: A case report

Background Prostate cancer is the second most common solid tumor leading to membranous nephropathy (MN). Thrombotic microangiopathy (TMA) has been reported to be related to prostate cancer. Nonetheless, the association between prostate cancer and MN and TMA has not been well established. Case report A 73-year-old man presented with nephritic syndrome 40 days after implantation of iodine-125 seed for stage II T2N0M0 prostatic carcinoma. The prostatic-specific antigen (PSA) was normalized, and the tumor disappeared after the initial brachytherapy. The circulating autoantibody to phospholipase A2 receptor (PLA2R) and thrombospondin type 1 domain containing 7A (THSD7A) was undetectable. Kidney biopsy revealed MN and TMA in glomerulus. Staining of PLA2R, THSD7A, prostate-specific membrane antigen, and prostate acid phosphatase in glomeruli were all negative. The diagnosis of MN and TMA was made, and a combination of steroid therapy and tacrolimus was prescribed. Two weeks after immunosuppressive treatment with prednisone 30 mg/d and tacrolimus 2 mg/d, the patient achieved partial remission in terms of proteinuria. Conclusion This case study was the first report of MN with TMA as manifestations in patients with prostate cancer after I-125 seeds implantation. We hypothesize that prostate cancer may cause MN and TMA, and the mechanism behind this relationship merits further study. .