Kidney Week

Abstract: PUB167

A Rare Case of Concurrent Glomerulopathies: Atypical Anti-GBM Disease and Phospholipase A2 Receptor (PLA2R) Antibody-Negative Membranous Nephropathy

Session Information

• Publication Only

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Tandon, Ariv, CORE Kidney Program, UCLA Health, Los Angeles, California, United States

Ariv Tandon

• Krivitsky, Sofia, CORE Kidney Program, UCLA Health, Los Angeles, California, United States

Sofia Krivitsky

• Sayal, Anaya, CORE Kidney Program, UCLA Health, Los Angeles, California, United States

Anaya Sayal

• Chinta, Surabhi S., CORE Kidney Program, UCLA Health, Los Angeles, California, United States

Surabhi S. Chinta

• Sheth, Kiera, CORE Kidney Program, UCLA Health, Los Angeles, California, United States

Kiera Sheth

• Rastogi, Anjay, CORE Kidney Program, UCLA Health, Los Angeles, California, United States

Anjay Rastogi, MD, PhD

Introduction

Atypical anti-GBM is distinguished by linear IgG deposition along the glomerular basement membrane (GBM) and the absence of circulating anti-GBM antibodies. The rare coexistence of atypical anti-GBM disease and PLA₂R-negative membranous nephropathy (MN) suggests a possible secondary immune-mediated process, prompting uncertainty about the pathogenesis.

Case Description

A 69-year-old woman with a history of HTN and anxiety was hospitalized with flu-like symptoms and is found to have AKI and acute-on-chronic anemia. Initial evaluations demonstrated nephrotic-range proteinuria and IgA lambda monoclonal gammopathy. Secondary serologic workup further supported these findings, prompting concern for plasma cell dyscrasia, amyloidosis, and monoclonal gammopathy of renal significance.

Renal biopsy confirmed atypical anti-GBM disease along with PLA₂R-negative MN, but no definitive monoclonal-related renal process. Atypical anti-GBM disease presents with variable glomerular findings, including an MPGN pattern (Figure 1). The biopsy shows rare crescents, but not the severe crescentic process typically seen in typical anti-GBM disease.

Management includes carvedilol for blood pressure, sodium bicarbonate for metabolic acidosis, and pRBC transfusion for anemia. Retacrit was deferred pending hematologic workup for IgA lambda monoclonal gammopathy. Plasma cell-directed therapy was withheld as bone marrow findings were not diagnostic, and rituximab was considered for high-risk MN pending exclusion of secondary causes.

Discussion

IgA lambda monoclonal gammopathy shouldn’t be assumed to be the cause of the patient's AKI, anemia, and nephrotic-range proteinuria without a renal biopsy. Differential diagnoses included MGRS, amyloidosis, multiple myeloma-related kidney disease, and MN. The patient’s nephrotic-range proteinuria was likely driven by subepithelial immune-complex deposition, while the AKI may have reflected superimposed atypical anti-GBM activity. Renal biopsy and serological tests should be used in combination to diagnose MN with anti-GBM.

Figure 1: MPGN Pattern of Injury