The coexistence of membranous glomerulonephritis and its cause in the same biopsy: the two faces of IgG4-related kidney disease

Francesco Fortarezza,Loreto Gesualdo,Leonardo Resta,Domenico Piscitelli,Michele Rossini,Roberta Rossi,Maria Grazia Fiore

doi:10.34172/jnp.2021.45

Francesco Fortarezza, Loreto Gesualdo + Show 5 more

Open Access

https://doi.org/10.34172/jnp.2021.45

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Abstract

IgG4-related disease (IgG4-RD) is a systemic immune-mediated disease characterized by fibroinflammatory tumor-like masses that show the peculiar morphological features of storiform fibrosis, lymphoplasmacytic infiltrates rich in IgG4 positive plasma cells and obliterans phlebitis. The disease affects virtually any organ or apparatus and is often associated with increased serum IgG4 levels. Many previously described conditions (e.g. autoimmune pancreatitis, Mikulicz’s syndrome, Küttner’s tumor, and Riedel’s thyroiditis) are now classified to be part of IgG4-RD with the characteristic clinic, serologic and pathologic features. The kidney represents an important target-organ of the disease, mainly as tubulointerstitial nephritis (TIN). Nevertheless, some cases of glomerular disease, especially membranous glomerulonephritis (MNG), have been described in IgG4-related TIN. We report a case of IgG4-related kidney disease in which the two pathological patterns, TIN and MNG, were observed simultaneously in the same biopsy.

Highlights

IgG4-related disease (IgG4-RD) is a recently described systemic immune-mediated disease
Renal involvement by IgG4-RD is usually represented by an IgG4-related tubulo-interstitial nephritis (TIN) but cases of glomerular disease, especially membranous glomerulonephritis (MNG), have been reported in some case series of IgG4-related TIN (1)
IgG4 forms weaker interchain disulfide bridge (i.e. “Fab arm exchange”) resulting in asymmetrical, bispecific antibodies with two different antigen binding sites, which contributes to its anti-inflammatory activity (7)

Summary

Introduction

IgG4-related disease (IgG4-RD) is a recently described systemic immune-mediated disease. It can affect nearly any organ or apparatus and arises as pseudo-tumoral mass, often associated with increased serum IgG4 levels. Renal involvement by IgG4-RD is usually represented by an IgG4-related tubulo-interstitial nephritis (TIN) but cases of glomerular disease, especially membranous glomerulonephritis (MNG), have been reported in some case series of IgG4-related TIN (1). Case Presentation We reported the case of a 28-year-old man with a nephrotic syndrome. After an antibioticresistant fever, the patient underwent a contrast-enhanced computed tomography (CT) that showed a bilateral thickening of the pulmonary parenchyma, thoracic and iliac lymphadenopathies, mild splenomegaly and hepatomegaly. Surgery was performed and the histopathological examination (performed in another hospital) confirmed the clinical diagnosis of retroperitoneal abscess.

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