Abstract: SA-PO0712
A Case of Paraneoplastic Immune Complex-Mediated Membranoproliferative Glomerulonephritis Due to High-Grade Prostate Small-Cell Neuroendocrine Carcinoma
Session Information
- Glomerular Diseases: Complement-Mediated Glomerulopathies and Infection-Related GN
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Ramaswami, Akshaya, Yale School of Medicine, New Haven, Connecticut, United States
- Joseph, Teresa, Yale School of Medicine, New Haven, Connecticut, United States
- Luciano, Randy L., Yale School of Medicine, New Haven, Connecticut, United States
Introduction
Immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) is a rare, progressive glomerulopathy mediated by immune complex deposition and complement overactivity. It may be idiopathic or secondary to infection, neoplasm, paraproteinemia and autoimmune disease. Paraneoplastic IC-MPGN is usually associated with hematologic cancers. Among solid tumors, MPGN is most frequently reported in colorectal cancer. There is only 1 reported case of prostate cancer causing paraneoplastic MPGN. We present a rare paraneoplastic IC-MPGN due to a prostatic neuroendocrine tumor.
Case Description
An 84 year-old man with type 2 diabetes, Charcot’s foot with multiple metatarsal head resections, CKD stage 3 who presented with 4 weeks of dark urine, slow urine stream and weight loss. Laboratory findings were significant for peak creatinine of 9.3 mg/dL, hematuria and proteinuria with predominant albuminuria. CT abdomen and pelvis showed a mass suspicious for advanced prostate cancer with lymph node biopsy showing high-grade neuroendocrine prostate carcinoma. He underwent nephrostomy tube placement for moderate hydroureteronephrosis but remained anuric. Renal biopsy showed increased glomerular and mesangial cellularity with matrix deposition, immunofluorescence was positive for IgM, IgA, IgG, C3. Electron microscopy showed thickened GBM with 100% foot process effacement, hump-like subepithelial and subendothelial deposits. Despite the subepithelial deposits seen on biopsy, no infectious etiology was found to support an infection-associated GN. Thus, findings were thought to be secondary to a paraneoplastic IC-MPGN due to the neuroendocrine tumor. He was treated with an ineffective steroid taper and is hemodialysis-dependent. He is being treated with carboplatin and etoposide.
Discussion
IC-MPGN is a rare paraneoplastic manifestation with few reported cases in solid organ tumors. It is an aggressive glomerulopathy with a 15-40% kidney failure risk within 10 years. IC-MPGN on biopsy typically stains positive for immunoglobulins and complements, especially C3, with activation of the classical complement pathway. The cornerstone of the treatment of secondary IC-MPGN is management of the underlying cause. RAS inhibition, rituximab and steroids have been tried. Complement inhibition is actively being studied but is not approved for treatment yet.