PathPointers highlight important everyday teaching points when reviewing kidney histology. These brief and easy-to-read blog posts include real clinical images to demonstrate various biopsy findings.

Summer marks the graduation of nephrology fellows and welcoming of new ones. In this post, we will provide an image-rich, pattern-based approach to glomerular disease in kidney biopsies. Many others are available elsewhere; Fundamentals of Renal Pathology, by Fogo et al is also an excellent resource.

Light microscopy

• Are glomeruli normal or abnormal? (Figure 1)
• Is there too much matrix, too many cells, or both?
• Where is the abnormality?
  • Mesangium (Figure 2, 4)
  • Capillary loops (Figure 3, 4, 5)
  • Bowman’s space (Figure 5, 6)
• Does the abnormality involve all of the glomerular tuft (global) or part of it (segmental)? (Figure 6)
• Do the abnormalities involve all glomeruli (diffuse, >50%), or some of them (focal, <50%)?

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Immunofluorescence microscopy

• Deposit type (Figure 7)
  • IgG, IgM, IgA, kappa light chain, lambda light chain, complement C3, complement C1q
• Deposit location (Figure 7)
  • Mesangium, capillary loop, outside glomeruli

Electron microscopy

• Deposit location (mesangium, subendothelial, subepithelial) (Figure 7)
• Deposit substructure, if present
• Glomerular basement membrane abnormalities, if present
• Supportive or unexpected findings

Integrate

• Correlate with clinical, lab, systemic features
• Degree of activity and chronicity
• Do the findings provide an anatomic etiology for the observed clinical abnormality and reason for biopsy? (If not, why not? What are the pertinent negatives?)

Figure 7

– Post prepared by Nicole Andeen, AJKDBlog Contributor