Podocytic Infolding in Glomerular Basement Membrane: Clinicopathological Study of 31 Cases
Tsukasa Suzuki, Taichiro Yoshimoto, Noriyoshi Fukushima. Jichi Medical University Hospital, Shimotsuke, Tochigi, Japan
Background: Recently, podocytic infolding into the glomerular basement membrane (GBM) observed by electron microscopy (EM) has been noted as a unique pathological finding. In relation to this, various deposition in the GBM including microstructure such as microtubule and microsphere structures around the podocyte and subendothelial deposits were also observed in. However the clinicopathological significance of these phenomena is not well known.
Design: Among 3230 renal biopsies performed in our hospital from 1995 to 2011, we have identified 31 cases with podocytic infolding (depth over 100nm) into the GBM according to the EM findings. Before analysis, we classified them into three groups; podocytic infolding only (group I), podocytic infolding with microstructure (group II) and podocytic infolding with subendothelial deposit (group III). In addition to the clinicopathological analysis, we measured GBM thickness, infolding depth and their ratio in EM observation.
Results: The median patients' age was 60 years (range 8-84). 19 patients were men and 12 women. All 31 patients showed proteinuria and nephrotic syndrome, but none showed macrohematuria. Two patients showed increased serum creatinine levels (sCr) (>1.14mg/dl). The diagnoses were as below; 23 of 25 cases were membranous nephropathy (MN) and collagen disease in group I (n=15) and II (n=10), and all cases were MN in III (n=6). The median urinary protein excretion and sCr were less in group II than I and III, (p value 0.0694, 0.1209 respectively). In immunofluorescence study, we found negative for immunoglobulin and complement in two cases. In EM findings, podocytic infolding was accompanied with GBM thickening in 29 of 31 cases. The median infolding depth/GBM thickness were 500/1000nm in group I, 322/808nm in group II and 400/1085nm in group III. The median ratio were 51.7% in group I, 38.5% in group II and 36.7% in group III. The median size of microstructure in group II was 100nm in diameter. In group II, podocytic infolding situated within lamina rara externa in all cases.
Conclusions: Podocytic infolding with microstructure(group II) has different clinicopathological features from that without microstructure. The microstructure in podocytic infolding may have a finding in recovery stage from glomerular damage.
Category: Kidney (does not include tumors)
Monday, March 4, 2013 1:00 PM
Poster Session II # 249, Monday Afternoon