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. 2023 Apr 5;7(1):6.
doi: 10.1186/s41927-023-00330-1.

Chasing the Zebra: a case of membranous-like Glomerulopathy with SSA/RO52 deposits and no overt connective tissue disease

Savino Sciascia  1   2 , Paolo Miraglia  3   4   5 , Massimo Radin  3   4 , Manuela Giarin  6 , Nicolas Charbonier  6 , Antonella Barreca  6 , Irene Cecchi  3   4 , Irene Lanzetta  3   4 , Roberta Fenoglio  3   4 , Elisa Menegatti  5 , Dario Roccatello  3   4
Affiliations

Chasing the Zebra: a case of membranous-like Glomerulopathy with SSA/RO52 deposits and no overt connective tissue disease

Savino Sciascia et al. BMC Rheumatol. .

Abstract

Background: The nature of the deposits in immune-mediated glomerulonephritis with a membranous pattern and masked IgG-Kappa deposits (MGMID) remains still to be elucidated.

Case presentation: We present a case of 33-year-old woman developing a continuous asymptomatic proteinuria (0.8-1 g/24 h) with no overt connective tissue diseases. She tested positive at high titers for SSA antibodies (Ro52 838 UI/mL, Ro60 2716 UI/mL) and at the kidney biopsy histological findings were compatible with an immune-mediated glomerulonephritis with a membranous pattern and masked IgG-Kappa deposits. Also, we demonstrated a positive immunohistochemistry staining for anti-Ro52-SSA antibodies, with a granular positivity in mesangium and along rare glomerular capillaries. To date, only one case of a patient with overt diagnosis of Sjögren's syndrome with MGMID has been described but a pathogenic role for SSA and SSB antibodies has never been proven.

Conclusions: In this case, we described for the first time by immunohistochemistry a Ro52+ granular positivity in the mesangium and glomerular capillaries, potentially paving the way for a better understanding of MGMID.

Keywords: Autoantibodies; Membranous Glomerulonephritis and Masked IgG-Kappa deposits; Membranous nephropathy; SSA.

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Conflict of interest statement

The authors declare that there are no conflicts of interest. S.S. is a member of the editorial board for the BMC Rheumatology journal.

Figures

Fig. 1
Fig. 1
Renal biopsy findings in membranous-like glomerulopathy with masked IgG kappa deposits. Immunofluorescence on fresh tissue showed irregular moderate granular staining for IgG (A) along the glomerular capillaries only in limited basement membranes and rare mesangial deposits. Glomeruli revealed positivity for only kappa light chain (B) and not for lambda (C) (A–C direct immunofluorescence on fresh material, original magnification × 400). Serum amyloid P (SAP) demonstrated stronger and more diffuse staining in glomeruli with a similar granular pattern (D, direct immunofluorescence on fresh tissue, original magnification X 400). E Occasional spikes and holes were evident along the glomerular basement membranes by Jones methanamine silver stain (original magnification × 200; scanner Hamamatsu). F Immunohistochemistry on fixed material with anti-human C4d antibody demonstrated strong granular positivity along glomerular capillary walls with a diffuse but irregular distribution and occasional mesangial deposits (original magnification × 200; scanner Hamamatsu). Glomeruli were negative both for PLA2R (G, original magnification × 200; scanner Hamamatsu) and THSD7A (H, original magnification × 200; scanner Hamamatsu). I, J) Electron microscopy demonstrated sparse amorphous subepithelial deposits along the glomerular basement membrane with occasional spikes and rare mesangial deposits (I,J original magnification × 9800. TEM Philips CM10)
Fig. 2
Fig. 2
Ro52 immunohistochemistry. Granular positivity in mesangium and along rare glomerular capillaries. Controls biopsy from patients with lupus nephritis and SSA serological positive antibodies resulted in negative at immunohistochemistry for Ro52
See this image and copyright information in PMC

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