A case of membranous nephropathy during asymptomatic syphilis.

We experienced membrane nephropathy associated with syphilis infection. A 51-year-old woman had an increase in body weight with leg edema. Blood and urine examination showed low serum protein and heavy proteinuria. She was diagnosed with nephrotic syndrome. The light microscope showed normal glomeruli with no bubbling appearance or spike lesions. Immunofluorescence analysis on the renal biopsy sample showed granular deposition of IgG, C3, C1q, κ and λ on capillary walls. The electron microscope showed a hump-like subepithelial and mesangial electron-dense deposit. Her pathologic diagnosis was Ehrenreich-Churg stage I membrane nephropathy. Negative staining of IgG4 on glomerular walls indicates secondary membrane nephropathy. The immunology test indicated active syphilis infection despite the lack of any skin lesions or constitutional symptoms related to syphilis. NDNF, which was recently identified as an antigen of syphilis-associated MN, was positive on capillary walls. The antibiotic treatment led to rapid, complete remission without using immunosuppressive treatment.