1. Count all glomeruli, determine the number of sclerotic glomeruli

Normal renal cortex. H&E

Normal Glomerulus

Normal Glomerulus

GLOBAL SCLEROSIS (PAS)

Glomerular obsolescence (count as sclerotic)

SEGMENTAL SCLEROSIS (PAS)

Should be rare in Loop biopsies

Mesangial expansion, hypercellularity

You can note it but not important if mild

Nodular mesangial sclerosis (PAS)

Means that the donor was diabetic. Should be noted, very rarely occurs

Glomerular capillary microthrombi (Trichrome)

Glomeruli fibrin thrombi are common in brain trauma; they indicate donor DIC.Report it, but these thrombi go away quickly in the recipient

2. Estimate degree of interstitial fibrosis

• Mild: up to 25% of cortex (do not consider medulla)

• Moderate 25-50% of cortex• Severe: Over 50%

• Note inflammation (usually mild and patchy in fibrotic areas), if present

Severe interstitial fibrosis (right side is intact)

This entire area is fibrotic

3. Examine vasculature• Note arteriolar hyalin• Note intimal thickening

– Mild: if less than thickness of the media– Moderate: Thicker than the media– Severe: More than twice the thickness of the media

with luminal narrowing• Note severe obliterative intimal thickening

(usually kidney will be discarded• Note arterial/arteriolar thrombi – Thrombotic

microangiopathy (TMA) – rare in donors but bad

Normal arteriole

Severe arteriolar hyalin

Normal intrarenal artery

Intimal thickening

Thrombotic microangiopathy with luminalobliteration

TMA with obliterated lumen and fragmented RBCs

TMA with severe mucoid thickening of a small artery

Conclusions

• Do not give diagnosis• Be descriptive• Acute tubular necrosis (ATN) is common

in loop biopsies. If severe, you can comment on it (prominently thin tubular epithelium, lots of debris in tubular lumina) but it is reversible and if not striking do not mention it