Fig 1.
Putative origin of paratubular basement membrane insudative lesions.
In most patients, adhesion of the glomerular tuft to the glomerulotubular junction (arrow) was observed, followed by subsequent formation of insudative lesions from the glomerular tubular pole to the proximal convoluted tubule. Original magnification: x 400. Bar = 50 μm. Periodic acid methenamine silver stain.
Fig 2.
A-F. Paratubular basement membrane insudative lesions (PTBMIL) extending from the glomerulotubular junction to the proximal convoluted tubule. Serial sections revealed that PTBMIL (arrows) developed from the abnormal glomerulotubular junction and extended to the proximal convoluted tubule. Original magnification: x 200. Bar = 100 μm. Masson trichrome stain.
Fig 3.
A-D. Progression of paratubular basement membrane insudative lesions (PTBMIL) from cortex to medulla. Serial sections revealed that some PTBMIL extended from the glomerular tubular pole in the cortex to the proximal straight tubule in the medulla, and development of PTBMIL paralleled the severity of tubular atrophy. Original magnification: x 200. Bar = 100 μm. Masson trichrome stain.
Fig 4.
A-E. Histological features of paratubular basement membrane insudative lesions (PTBMIL). A-C: Duplication of the tubular basement membrane (TBM) formed by PTBMIL. On periodic acid Schiff (PAS), periodic acid methenamine silver (PAM), and Masson trichrome (MT) stain, duplication of the TBM formed by PTBMIL (arrows) generally coexists with tubular atrophy. A; PAS stain, B; PAM stain, C; MT stain. Original magnification: x 400. Bar = 50μm. D and E: Electron microscopy findings. PTBMIL containing granular and lamellar dense body deposits (white arrows) are located between the thin newly-formed TBM (black arrows) and the thicker primary TBM (red arrows) of the proximal tubule. Original magnification: x 2000, bar = 15μm.
Fig 5.
A-D. Grades of paratubular basement membrane insudative lesions (PTBMIL). A: Grade 1 in cortex and medulla. PTBMIL was observed in >0% and <25% of tubules of each lesion. Original magnification: x 200. Bar = 100μm, periodic acid methenamine silver (PAM) stain. B and C: Grade 2 in cortex and medulla. PTBMIL was observed in 25–50% of tubules of each lesion. Original magnification of B and C: x 200. Bar = 100μm, PAM stain. D: Grade 3 in cortex and medulla. PTBMIL was observed in >50% of tubules of each lesion. Original magnification of 3D: x 200. Bar = 100μm, PAM stain.
Table 1.
Baseline histopathologic findings in all patients and patients stratified by PTBMIL group, and correlations between PTBMIL score/group and other pathologic findings.
Table 2.
Baseline clinical parameters of all patients and each PTBMIL group.
Table 3.
Comparison of the main clinical parameters between baseline and during follow-up (or at final follow-up) in all patients and among PTBMIL groups.
Fig 6.
Renal survival rate stratified by PTBMIL group.
The estimated 2-year renal survival rate was 83% in PTBMIL group 1, 56% in PTBMIL group 2, and 26% in PTBMIL group 3. There were significant differences of the renal survival rate between the different PTBMIL groups. Outcome: ≥40% decline of estimated glomerular filtration rate or dialysis due to end-stage renal disease. The log-rank test was used for survival analysis. Abbreviations: PTBMIL: paratubular basement membrane insudative lesions.
Table 4.
Univariate and multivariate Cox proportional hazard models incorporating PTBMIL group and Harrell’s C-index of models with or without the PTBMIL group/PTBMIL score.