Progressive glomerulopathy with unusual deposits of striated structures: a new disease entity?

A 68-year-old man developed proteinuria and renal insufficiency. A renal biopsy showed mesangial proliferation and double contour in almost all glomeruli. Congo red staining for amyloid was negative. Immunofluorescence microscopy revealed no deposition of immunoglobulins. Electron microscopy showed unusual deposits of striated structures mainly in the subendothelial space and the mesangium. These deposits contained regularly stacked straight electron-dense bands. Microfilament-like deposits were also observed. The patient did not respond to steroid therapy and developed end-stage renal disease. All known disease entities with non-amyloid non-immunoglobulin-derived organized glomerular deposits were excluded. Progressive glomerulopathy in our patient might be a new disease entity.