Case of immunotactoid glomerulopathy showing high responsiveness to steroids therapy despite severe pathological features

Abstract

A 72-year-old woman presented with nephrotic proteinuria and moderate haematuria. Renal pathology was compatible with immunotactoid glomerulopathy (ITG), for which there is no consensus for appropriate therapy. We, therefore, postponed immunosuppressive therapy. After 4 years, the patient's renal function started to decline and renal pathology was re-evaluated, revealing a pathological change from mesangial proliferative glomerulonephritis to endocapillary proliferative glomerulonephritis. Treatment with oral prednisolone (30 mg/day) was initiated. Within 5 weeks, complete remission of proteinuria was obtained (proteinuria 6.02 g/gCr to 0.12 g/gCr), and the patient's renal function stabilised. Generally, responsiveness to immunosuppressive therapy is poor in patients with ITG, and the present case represented a very rare clinical course. Some previous cases have indicated susceptibility to the therapy, regardless of the severity of renal damage. As a possible distinct entity that determines susceptibility to immunosuppressive therapy, we suggest the presence of a latent lymphoproliferative disease with no significant haematological symptoms.

Keywords: nephrotic syndrome; pathology; proteinurea.

Figure 1

(A,B) Light microscopic findings from the first biopsy showed diffusely increased mesangial matrix and cells to a mild extent without mesangial interposition. (A) Periodic acid-Schiff. 400×  and (B) Periodic acid-Schiff-methenamine silver. 400×. (C) Electron microscopic findings showed dense deposits in the mesangial matrix, which had hollow cores and were arranged in parallel arrays with an average diameter of 40 nm at a higher magnification (4000×, 40 000×).

Figure 2

(A,B) Light microscopic findings from the second biopsy showed membranoproliferative glomerulonephritis with lobular accentuation, and endocapillary proliferative change. (A) Periodic acid-Schiff. 400×. (B) Periodic acid-Schiff-methenamine silver. 400×. (C,D) Electron microscopic findings showed dense deposits in the mesangial areas and subendothelial space. Higher magnification revealed hollow-centred microtubular structures of 35–45 nm diameter in these deposits. (C) The white line corresponds to 2 µm. (D) The white line corresponds to 500 nm.

Figure 3

Immunofluorescence findings from the second biopsy showed dominant C1q positivity on the capillary and reduced intensity in the mesangial areas. IgM and C3 were also positive in the capillary, while IgG, IgA and C4 were faintly positive in the capillary in a segmental manner.

Figure 4

Changes over time in uTP/Cre and eGFR after the initiation of treatment. On day 36, complete remission of proteinuria was obtained (uTP/Cr=0.12 g/gCr). eGFR, estimated glomerular filtration rate.