Case Report

Primary Membranous Nephropathy Associated With Malignancy: A Case Report

by Rui Zhi NG1*, Tze Wei CHNG2, Chee Yong NG1

1Department of Renal Medicine, Changi General Hospital, Singapore.

2Department of Renal Medicine, Singapore General Hospital, Singapore.

*Corresponding author: Rui Zhi NG, Department of Renal Medicine, Changi General Hospital, Singapore.

Received Date: 20 November 2023

Accepted Date: 25 November2023

Published Date: 28 November 2023

Citation: Rui Zhi NG, Tze Wei CHNG, Chee Yong NG (2023) Primary Membranous Nephropathy Associated With Malignancy: A Case Report. Ann Case Report 08: 1527. https://doi.org/10.29011/2574-7754.101527.

Abstract

Membranous nephropathy is known to be associated with a wide range of conditions such as drugs, infection and malignancy. It is recommended to evaluate for associated conditions regardless of the presence of Anti-Phospholipase A2 Receptor (PLA2R) antibody which is known to be associated with primary membranous nephropathy. Our patient presented with nephrotic syndrome and a high serum anti-PLA2R antibody level. After discovering a rectal carcinoma on our secondary workup, we diagnosed him with secondary membranous nephropathy from malignancy and the patient was referred to a surgeon who resected the rectal cancer. Despite the cancer going into remission after the surgery, there was no improvement in the proteinuria or serum anti-PLA2R antibody level. We reconsidered the possibility of primary membranous nephropathy and treated him with immunosuppression. Follow up after treatment with immunosuppression showed improvement in the serum anti-PLA2R antibody level and proteinuria, and he has since gone into partial remission.

Introduction

Membranous nephropathy is a common cause of nephrotic syndrome in adults, accounting for about 20% of the cases [1]. In around 80% of patients with membranous nephropathy, there is no underlying cause and 20% are associated with medications or other diseases such as malignancy [2]. We report a case of membranous nephropathy associated with malignancy that ultimately turned out to be primary membranous nephropathy.

Case Report

A 75-year-old male with a history of hyperlipidemia, presented with testicular and bilateral lower limbs swelling of 2 days duration. He was found to have a systolic blood pressure of 183mmHg. Serum creatinine was 75umol/L with no baseline serum creatinine available for comparison. Serum albumin was 21g/L, urinalysis showed 13 red blood cells per high-power field, 6 white blood cells per high-power field and a urine protein creatinine ratio of 10.16g/g. Fasting plasma glucose was 4.8mmol/L and hemoglobin A1C was 5.5%. C3 level was 1.18g/L and C4 level was 0.17g/L. Serum and urine electrophoresis did not reveal a monoclonal band. He tested negative for the hepatitis B virus surface antigen, hepatitis C virus and human immunodeficiency virus. Testing for anti double-stranded DNA antibody, anti-proteinase 3, anti-myeloperoxidase antibodies were negative. Antinuclear antibody titre was borderline at 1:160. Anti-PLA2R antibody was positive at 840.54 RU/ml.

Kidney biopsy (Figure 1) revealed normal thickness of capillary walls and subtle vacuoles in the glomerular basement membrane on light microscopy. Immunofluorescence showed 3+ granular staining in the glomerular basement membrane for IgG and 2+ granular staining in the glomerular basement membrane for C3. PLA2R staining was weakly positive segmentally. Electron microscopy revealed subepithelial electron dense deposits.