Fogo, Ch. 13 - Acute interstitial nephritis

Question 1

What are some causes of acute interstitial nephritis?

Answer 1

Drugs, infection, humoral immune responses, even obstruction/reflux.

Question 2

How does acute interstitial nephritis present?

Answer 2

Acute oliguric renal failure. Can also have arthralgia, fever, eosinophilia, and rash (depending on cause).

Question 3

What are the gross findings in AIN?

Answer 3

Pale cortex and distinct corticomedullary junction.

Question 4

What are the LM findings in AIN?

Answer 4

Diffuse interstitial edema with mixed inflammatory infiltrate. Usually confined to cortex with distal > proximal tubulitis.

Question 5

What are the IF findings in AIN?

Answer 5

Usually nothing; may have some granular complement/fibrin. Can have some anti-TBM staining.

Question 6

What does neutrophilic infiltrate suggest in AIN?

Answer 6

A bacterial or otherwise infectious etiology.

Question 7

What do B-cells and granulomas suggest in AIN?

Answer 7

An allergic etiology.

Question 8

What features portend a worse outcome?

Answer 8

Interstitial fibrosis and tubular atrophy

Granulomata formation

Greater inflammatory infiltrate

Question 9

TINU

Answer 9

Tubulointerstitial nephritis with uveitis

Maybe related to mCRP

Question 10

IgG4 nephritis

Answer 10

Associated with salivary/lacrimal and pancreatic involvement with IgG4 plasma cells.