Fibrillary-immunotactoid glomerulopathy with renal deposits of IgAlambda: 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 glomerulonephritis with eosinophilic deposits. Electron microscopy showed organized, Congo-red negative deposits, forming microtubules of about 20 nm width in the capillary walls and in the mesangium, establishing a diagnosis of fibrillary-immunotactoid glomerulopathy. Fibrillary-immunotactoid glomerulopathy is a rare cause of glomerulonephritis, characterized by Congo-red-negative glomerular deposits of fibrils, sometimes organized in microtubules, predominantly containing IgG and C3. Patients clinically present with the nephrotic syndrome, hematuria and hypertension. The pathogenesis of this glomerulopathy has not been elucidated yet. In our patient, the renal deposits contained IgAlambda. This peculiar feature is suggestive of an underlying paraproteinemia. 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 patient was not treated with immunosuppressive drugs and he is currently progressing to end-stage renal disease.