This kidney exhibits several stones as well as chronic pyelonephritis.
In picture 1, the kidney has been cut in half and opened. You can see the stones, dark red and rough. They have plugged the renal collecting system and dilated the calyces. Stasis of urine and the presence of the inert stones themselves both promote infection. This in turn can make the stones grow larger.
The second photo shows scarring and shrinking of the renal tubules, with the glomerulus spared. In contrast to rapidly progressive glomerulonephritis, the scar is outside Bowman's capsule.
The third photo, a PAS stain, shows a group of tubules filled with cast protein and distended from scar contraction. The unwary may mistake this for thyroid.
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