Fogo, Ch. 14 - Chronic interstitial nephritis

Question 1

Name some causes of chronic interstitial nephritis

Answer 1

Reflux/obstruction, chronic infection, Sjogren’s, drugs, radiation, balkan nephropathy

Question 2

What are the gross findings in reflux-related chronic interstitial nephritis?

Answer 2

Dilated calyces and irregularly thinned parenchyma. Scars, contractions, and granular surface.

Question 3

How does the gross appearance of obstructive chronic IN differ from that of reflux-related?

Answer 3

In obstruction, the findings are more diffuse, whereas they are more irregular in reflux.

Question 4

What are the tubulointerstitial LM findings in chronic interstitial nephritis?

Answer 4

IFTA, tubular dropout, thyroidization.

Mononuclear inflammatory cells and lymphoid follicles.

Question 5

What are the vascular LM findings in chronic interstitial nephritis?

Answer 5

Intimal fibrosis and muscular hypertrophy. Can have glomerular ischemic changes.

Question 6

How does intrarenal reflux result in chronic interstitial nephritis?

Answer 6

Pyelotubular backflow (made possible by compound papillae) results in tubular rupture or forniceal tears which scar after a week or two.

Question 7

Why are children more prone to reflux nephropathy?

Answer 7

They have shorter ureters and more patent collecting ducts, allowing for more direct backflow damage.

Question 8

What are the findings in chronic pyelonephritis?

Answer 8

Less thyroidization of tubules, more neutrophils.

Question 9

What are the findings in xanthogranulomatous pyelonephritis?

Answer 9

Staghorn calculi

Pus, necrosis, friability

Foam and multinucleated giant cells

Question 10

Distinguish between malakoplakia and megalocytic interstitial nephritis.

Answer 10

Malakoplakia results from abnormal macrophage function (mass-forming) and features Michaelis-gutmann bodies.

Megalocytic interstitial nephritis: Basically malakoplakia without Michaelis-gutmann bodies