ANTI-PHOSPHOLIPASE A2 RECEPTOR ANTIBODY (PLA2R)-NEGATIVE MEMBRANOUS NEPHROPATHY ASSOCIATED WITH OMENTAL MESOTHELIOMA AND RETROPERITONEAL FIBROSIS

A COHEN1,  E VILAYUR 1

1Nephrology Department, John Hunter Hospital, New Lambton Heights, Australia

Background: Membranous nephropathy is identified in 70% of patients with malignancy-associated nephrotic syndrome. It also occurs in association with retroperitoneal fibrosis, being the most common IgG4-related glomerular disease. We present a case of membranous nephropathy associated with omental mesothelioma and retroperitoneal fibrosis, without evidence of IgG4-related disease, who went into complete remission with immunosuppressive therapy.

Case Report: A previously well 57-year-old male was referred with nephrotic syndrome, with urine albumin:creatinine ratio (ACR) 690mg/mmol and serum albumin 13g/L. Renal biopsy demonstrated anti-phospholipase A2 receptor antibody (PLA2R)-negative membranous nephropathy, consistent with secondary membranous nephropathy. Routine ultrasound incidentally showed an abdominal mass which was PET-avid. Laparoscopic biopsy revealed omental mesothelioma. Partial remission of proteinuria was achieved after resection and treatment with ACE inhibitors.

Further evaluation was postponed by an admission for a ST-elevation myocardial infarction. Nephrotic syndrome relapsed following the event, which was concerning for recurrence of mesothelioma.

Repeat PET scan showed new masses encasing the distal aorta, investigated with laparotomy and biopsy. Histopathology was consistent with retroperitoneal fibrosis without any omental mesothelioma or IgG4 disease. The patient also developed ureteric obstruction requiring insertion of bilateral ureteric stents.

He was commenced on prednisolone 40mg daily with monthly cyclophosphamide infusions. He entered complete remission of nephrotic syndrome, with reduction of urine ACR from 847mg/mmol to 40mg/mmol after 6 months of therapy. Maintenance therapy was with azathioprine 150mg daily and prednisolone 5mg daily. The urine ACR has remained < 30mg/mmol for 12 months.

Conclusion: PLA2R-negative membranous nephropathy can occur in the context of retroperitoneal fibrosis. It responds to immunosuppressive therapy. We propose that in our patient, retroperitoneal fibrosis and membranous nephropathy were both triggered by omental mesothelioma.


Biography:

Adrienne Cohen is a renal advanced trainee at John Hunter Hospital. She has a commitment towards quality improvement processes and improving the care we delivery to patients.

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