What are the key features to evaluate when examining a kidney pathology slide, including tubular and basement membrane changes, in order to interpret the results accurately?

From the Guidelines

To accurately interpret kidney pathology slides, it is essential to evaluate the overall architecture, noting the distribution and appearance of glomeruli, tubules, interstitium, and blood vessels, and to utilize special stains and immunofluorescence, as recommended by the Mayo Clinic/Renal Pathology Society consensus report 1. When examining kidney pathology slides, several key features must be evaluated to interpret the results accurately.

• The overall architecture of the kidney tissue should be noted, including the distribution and appearance of glomeruli, tubules, interstitium, and blood vessels.
• For tubules, their shape, size, and integrity should be examined, looking for signs of acute tubular necrosis, casts, or crystals.
• The basement membrane requires careful assessment, particularly in glomeruli, where thickening may indicate diabetic nephropathy or thinning might suggest Alport syndrome.
• In glomeruli, look for hypercellularity, crescent formation, mesangial expansion, or sclerosis, as described in the patterns of glomerulonephritis (GN) 1.
• The interstitium should be evaluated for fibrosis, inflammation, or edema, while blood vessels may show hyalinosis, arteriosclerosis, or vasculitis.
• Special stains are crucial for interpretation: PAS highlights basement membranes, silver stains show membrane details, trichrome identifies fibrosis, and Congo red detects amyloid.
• Immunofluorescence helps identify immune complex deposition patterns in glomerulonephritis, while electron microscopy reveals ultrastructural changes like foot process effacement in minimal change disease or immune deposits in membranous nephropathy, as outlined in the practice guidelines for the renal biopsy 1.
• Correlating these findings with clinical information is essential for accurate diagnosis and patient management, emphasizing the importance of a thorough understanding of renal disease and good communication between the nephropathologist and the nephrologists caring for the patients 1.

From the Research

Key Features to Evaluate in Kidney Pathology Slides

When examining a kidney pathology slide, several key features should be evaluated to interpret the results accurately. These features include:

• Tubular changes: such as tubular atrophy, tubular dilation, and tubular necrosis 2, 3, 4
• Basement membrane changes: such as thickening or thinning of the glomerular basement membrane 5, 6
• Interstitial changes: such as interstitial fibrosis, interstitial inflammation, and interstitial edema 2, 3, 4, 6
• Glomerular changes: such as glomerulosclerosis, glomerulonephritis, and glomerular capillary loop shrinkage 5, 4, 6

Tubular and Basement Membrane Changes

Tubular and basement membrane changes are critical features to evaluate in kidney pathology slides. These changes can indicate various kidney diseases, such as:

• Acute tubular necrosis (ATN): characterized by tubular necrosis and apoptosis 5
• Interstitial fibrosis and tubular atrophy (IFTA): characterized by interstitial fibrosis and tubular atrophy, often seen in chronic kidney disease (CKD) 2, 4
• Membranous nephropathy: characterized by thickening of the glomerular basement membrane 6

Evaluation of Kidney Pathology Slides

To evaluate kidney pathology slides accurately, the following steps should be taken:

• Examine the slide under a microscope to identify any abnormalities in the tubules, interstitium, and glomeruli
• Evaluate the degree of interstitial fibrosis and tubular atrophy
• Assess the presence and severity of glomerular changes, such as glomerulosclerosis and glomerulonephritis
• Consider the clinical presentation and laboratory results, such as proteinuria and hematuria, to correlate with the pathological findings 5, 3, 4, 6