Abstract: FR-PO983
Kidney Dysfunction in Hematologic Malignancy Unveiling Anti-brush Border Antibody Disease
Session Information
- Pathology and Lab Medicine - 1
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1800 Pathology and Lab Medicine
Authors
- Davis, Paul W., Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Buglioni, Alessia, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Larsen, Christopher Patrick, Arkana Laboratories, Little Rock, Arkansas, United States
- Cheungpasitporn, Wisit, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Titan, Silvia, Mayo Clinic Minnesota, Rochester, Minnesota, United States
Introduction
Anti-brush border antibody disease (ABBA) is a rare disorder where antibodies target the low-density lipoprotein receptor-related protein 2 (LRP2 or megalin). Despite its rarity, ABBA warrants consideration in the differential of renal injury of unknown etiology or when IgG deposits in the TBM are seen. We present a case of ABBA with malignancy discussing diagnosis and treatment.
Case Description
The patient, a 56 year-old-male with a PMHx of HTN, DM, stroke, and PE (on apixaban) presented with worsening renal function. Two years ago with normal sCr and Hgb levels, he had knee replacement complicated by infections, treated with long term antibiotics. Anemia persisted, prompting a bone marrow biopsy revealing LGLL, treated with cyclophosphamide.
Exam: normal BP, pallor and BLE edema. Labs: Hgb 9.1 g/dL, Cr: 1.9 mg/dL, eGFRcr 42 mL/min/BSA, cysC 2.1 mg/L, eGFRcys 29 mL/min/BSA and eGFRcrcys 34mL/min/BSA, glucose 156 mg/dL, urine: UACR 82 mg/g, UPCR 0.56 mg/mg, RBP 97905 mcg/24 hours, and negative for RBCs or Hgb; small serum monoclonal IgG kappa, positive ANA Hep-2 substrate 1:160, anti-DS DNA 145 IU/mL, positive lupus anticoagulant. Renal ultrasound: bilateral mild cortical thinning.
Kidney biopsy findings were consistent with ABBA disease.
Treatment: Prednisone and mycophenolate. Cr remains stable, Hgb is improved.
Discussion
This case emphasizes considering ABBA in the differential of AKI or CKD of unknown causes. It may occur alone or with systemic diseases, notably hematological malignancies and auto-immune conditions. Diagnosis relies on biopsy showing IgG TBM deposits, with positive IF staining for LRP2 within TBM or serologic confirmation of anti-LRP2 antibodies by indirect IF on normal kidney. High CKD progression risk stresses the need for researching biomarkers and treatment options.
Proximal TBM granular staining positive for IgG, kappa, lambda, and anti-LRP2