Phospholipase A2 receptor–associated membranous nephropathy in a patient with IgG4-related disease: A case report

RATIONALE: IgG4-related disease (IgG4-RD) is a multiorgan disease of unestablished prevalence that is characterized histopathologically by a dense lymphoplasmacytic infiltrate enriched with IgG4-expressing plasma cells and associated with storiform fibrosis. Tubulointerstitial nephritis (TIN) is the most common renal manifestation of IgG4-RD, but membranous nephropathy (MN) has also been described and often occurs in the context of concurrent TIN. Patients with IgG4-related MN have been characteristically negative for autoantibodies to the phospholipase A2 receptor (PLA2R). PATIENT CONCERNS: A 45-year-old man presented with abdominal pain and lower extremity edema. DIAGNOSIS: Histopathological evaluation of pancreas and liver biopsies established a diagnosis of IgG4-RD. Renal biopsy confirmed a diagnosis of PLA2R-associated MN without evidence of concurrent TIN. INTERVENTIONS: The patient was treated with rituximab, a short course of low-dose, oral cyclophosphamide, and a rapid glucocorticoid taper. OUTCOMES: The patient achieved remission of MN after 8 months of therapy and maintained remission of IgG4-RD. LESSONS: PLA2R-associated MN may be a rare manifestation of IgG4-RD. Systematic evaluation of larger cohorts of IgG4-RD patients for the presence of PLA2R autoantibodies and the investigation of PLA2R-associated MN cohorts for evidence of IgG4-RD would facilitate the understanding of the nature of the relationship between these observations.