Fibrillary-immunotactoid glomerulopathy with renal deposits of IgA lambda:a rare cause of glomerulonephritis

We describe a 24-year-old patient who presented with a nephrotic syndrome. His renal biopsy revealed a diffuse mesangioproliferative glomerulonephriti s with eosinophilic deposits. Electron microscopy showed organized, Congo-r ed negative deposits, forming microtubules of about 20 nm width in the capi llary walls and in the mesangium, establishing a diagnosis of fibrillary-im munotactoid glomerulopathy. Fibrillary-immunotactoid glomerulopathy is a ra n cause of glomerulonephritis, characterized by Congo-red-negative glomerul ar deposits of fibrils, sometimes organized in microtubules, predominantly containing IgG and C3. Patients clinically present with the nephrotic syndr ome, hematuria and hypertension. The pathogenesis of this glomerulopathy ha s not been elucidated yet. In our patient, the renal deposits contained IgA lambda. This peculiar feature is suggestive of an underlying paraproteinem ia. However, in the serum no paraproteins or cryoglobulins were found, and also microscopical examination and immunophenotyping of the bone marrow did not point to the presence of a monoclonal plasma cell dyscrasia. Our patie nt was not treated with immunosuppressive drugs and he is currently progres sing to end-stage renal disease.