Abstract: TH-PO683
Anti-brush Border Antibody Disease with Segmental Membranous Nephropathy and Acute Tubular Injury in a Patient with Severe Diabetic Nephropathy
Session Information
- Glomerular Diseases: Case Reports - 1
October 24, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Patel, Devansh H., The University of Alabama at Birmingham, Birmingham, Alabama, United States
- Chandramohan, Deepak, The University of Alabama at Birmingham, Birmingham, Alabama, United States
- Fatima, Huma, The University of Alabama at Birmingham, Birmingham, Alabama, United States
- Rajasekaran, Arun, The University of Alabama at Birmingham, Birmingham, Alabama, United States
Introduction
Autoantibody directed to the low-density lipoprotein receptor related protein 2 (LRP2), also known as megalin, is a newly recognized cause of human autoimmune tubular injury. This entity has been termed antibrush border antibody (ABBA) disease or anti-LRP2 nephropathy. LRP2 plays an important role in proximal tubular endocytosis of albumin and other molecules.
Case Description
A 64-year-old male with longstanding diabetes and recurrent AKIs on CKD4A3 presented with symptomatic volume overload and oliguric AKI. He was hypoalbuminemic [Sr albumin 1.5 g/dL] and had high grade proteinuria [UPCR ~ 12.5 g/g] on admission. Extensive serological workup was negative. Kidney biopsy revealed severe diabetes related kidney injury including mesangiolysis and microaneurysmal ruptures, segmental membranous nephropathy [IgG and light chains being 2+], and moderate acute tubular injury. Diffuse, homogenous appearing electron-dense deposits were noted along the TBMs. NELL-1 staining was negative along the GBM; LRP2 staining was positive along the TBM as well as segmentally in the glomeruli [membranous pattern] and along the Bowman's capsule. Patient continues to be dialysis dependent as of now. Immunosuppression was not started given his tenous overall condition.
Discussion
ABBA disease is extremely rare seen in 0.05% of all kidney biopsies. It most commonly afflicts elderly White males; 41% cases have concomitant monoclonal gammopathies. Its co-occurance with severe diabetic nephroapthy is not well ascribed. Acute tubular injury, granular TBM deposits in the proximal tubule, and segmental deposits in the subepithelial region and Bowman's capsule [seen in 80%] are charecteristic. Confirmation warrants positive IF staining for LRP2 within TBM deposits or serologic confirmation of anti-LRP2 antibodies by indirect IF performed on normal human kidney. Prognosis is guarded with 53% progressing to ESKD. Immunosuppression may be warranted in most cases. Our case highlights the importance of considering ABBA disease in the differential when diffuse TBM injury is noted.