Microlamellar structures in lobular glomerulonephritis associated with monoclonal IgG lambda paraproteinemia. A case report and review of the literature.

We report a 49-year-old woman who developed lobular glomerulonephritis with prevalent deposition of material positive for IgG, C1q and lambda light chain, but which was not stained by Congo red. Glomeruli revealed massive electron-dense deposits with a microlamellar structure in the mesangial matrix and peripheral capillary loops. Clinically, the patient had nephrotic syndrome, microhematuria and hypertension. No Bence-Jones protein or cryoglobulin was found in the urine or serum. Anti-DNA antibody was positive, but systemic lupus erythematosus (SLE) was ruled out by repeated serological examinations. Immunoelectrophoresis of blood and urine revealed increased IgG-lambda paraprotein, but no free light chains were found. We reviewed 54 cases reported in the literature, which showed organized crystalline structures on ultrastructural examination, but were unassociated with amyloidosis, SLE, cryoglobulinemia or multiple myeloma. The present patient is the first reported to have exhibited a combination of glomerulonephritis with organized deposits, monoclonal IgG lambda paraproteinemia, and the presence of anti-DNA antibody.