Not Your Typical Membranous Nephropathy

Introduction: “Full-house” (FH) immunofluorescence (IF) staining pattern on kidney biopsy is synonymous with lupus nephritis. However, rare cases with a similar pattern have been reported in non-lupus glomerulonephritides, including membranous nephropathy (MN). We report a case of MN with dual positivity for PLA2R and NELL1, along with a FH staining pattern on kidney biopsy. Case Description: 50-year-old male presented for evaluation of proteinuria (Fig 1.). No over the counter medications or illegal drug use noted. Blood pressure was 167/94 mmHg. Lab work showed serum creatinine 2.47 mg/dL (baseline ~1.6 mg/dL), Albumin 1.8 mg/dL, urine protein to creatinine (UPCR) 16,976 mg/g, urine albumin to creatinine 8,431 mg/g. Anti-PLA2R was markedly elevated at 532 RU/ml, complement level (C3 and C4) was normal. Syphilis, HIV, hepatitis B and C, anti-nuclear antibody, extranuclear antibody, anti-double stranded DNA, monoclonal gammopathy, cancer screening were negative. Kidney biopsy (Fig 2.) revealed MN stage III – IV, with +PLA2R, +NELL-1, and FH IF staining pattern. Patient was treated as primary MN and initiated on Mycophenolic Acid (MPA) given proliferative changes on biopsy, while pending Rituximab infusions. Discussion: Dual positivity for NELL1 and PLA2R, along with FH IF pattern in MN has not been previously reported. NELL1 has been linked to secondary MN. Non-Lupus FH staining pattern has been suggested as a early indicator of systemic lupus erythematosus.The presence of overlapping features on kidney biopsy in MN may warrant close clinical monitoring for emerging secondary causes of MN.