Fibrillary Glomerulonephritis Combined with Chronic Inflammatory Demyelinating Polyneuropathy

A 58-yr-old man presented with leg edema and subacute weakness of his bilateral lower extremities. Urinary and serum immunoelectrophoresis revealed the presence of lambda-type Bence Jones proteins. He was ultimately diagnosed with monoclonal gammopathy of undetermined significance (MGUS). A renal biopsy specimen showed fibrillary glomerulonephritis (FGN), which was randomly arranged as 12–20m nonbranching fibrils in the basement membranes. Immunofluorescence studies were negative for immunoglobulin (Ig)G, IgM, IgA, C3, and kappa light chains in the capillary walls and mesangial areas. A Congo red stain for amyloid was negative. Electromyography and nerve conduction velocity examinations results were compatible with the presence of demyelinating polyneuropathy. This case showed a rare combination of FGN, without Ig deposition, and MGUS combined with chronic inflammatory demyelinating polyneuropathy (CIDP).