Path - Tubulointerstitial Disease 1 Flashcards
4 types of tubulointerstitial diseases of the kidney
- Acute tubular necrosis (ATN)
- Pyelonephritis
- Interstitial nephritis
- Cystic diseases
What is the relationship between acute tubular necrosis (ATN) and acute kidney injury (AKI)?
ATN is a subset of AKI. It is considered to be the worst cases of AKI. Unknown % of AKI.
What percentage of AKI is due to ATN?
Unknown percentage because renal biopsies are rarely performed
What is the relationship between ATN and ischemia?
Ischemic ATN is a subset of ATN, roughly 75% of ATN
What % of ATN is due to ischemia?
Roughly 75%
What is the gross pathology of a kidney with ATN?
- Enlarged, up to 30% above normal
- pale cortex
- Congested medulla, especially at corticomedullary junction
A subset of kidneys with ATN will have what gross pathologic feature? When, how, and why?
Certain subset of ATN may have some cortical hemorrhages
Cortical hemorrhages occur due to uneven disease process. If patient develops thromboemboli or septic emboli.
What portion(s) of the renal tubule are most vulnerable to acute ischemic necrosis? Why?
- Proximal straight tubule
- Ascending thick limb of LOH
These two portions are in the outermost medulla at the corticomedullary junction, the area that gets congested with acute tubular necrosis
Describe normal renal tubule cells?
Cuboidal cells with granular eosinophilic cytoplasm
Pathology. What is the earliest morphologic change of tubular cell injury?
blebbing of luminal side cell membranes, indicates an early ischemic change
Pathology. Besides blebbing, what is another sign of early ischemic change in ATN?
Vacuolization of cytoplasm as a result of diffuse edema of tubular cells
Name the 2 reversible changes that are associated with ATN?
Blebbing and vacuolization, both are reversible.
What else can cause vacuolization of cytoplasm in tubular cells?
Osmotic diuresis
Pathology. In ATN, what is the next pathologic change in tubules after they have started blebbing and undergone vacuolization of the cytoplasm?
After blebbing and vacuolization:
- tubule cells will start to lose their brush border and begin to flatten out (seen in tubules 1-3)
- followed by necrosis & sloughing of epithelial cells (seen in 4)
Pathology. In ATN, the necrosis and sloughing of tubular cells leads to what?
The tubular cells mix into casts with proteinaceous material (seen in the arrows)
Buzzword. U/A casts in ATN?
muddy brown granular casts seen in UA
In ATN, besides coagulative necrosis that occurs in tubular cells, what else can occur? Why does this occur?
Besides coagulative necrosis, tubular cells can undergo apoptosis. Nichols explains this as the tubular cell sees that coagulative necrosis coming and decides to kill themselves before that happens.
The apoptotic renal tubular epithelial cells are most likely to have decreased cytoplasmic activity of what?
BCL-2
BCL-2 is considered an anti-apoptotic protein; therefore, if you have increased apoptosis, you would have decreased activity of BCL-2
Pathology. In ATN, what other protein could be found in the tubular lumen, especially in instances of crush injury?
Myoglobin released from muscle cells due to crush injury/trauma can cause rhabdomyolysis.
If a patient ingests ethylene glycol (antifreeze), what chemical compound will cause ATN?
Calcium oxalate
In ATN, what feature on microscopy indicates that tubular cells are in recovery phase?
Presence of mitotic figures
In ATN, how is it considered to be reversible? What symptom will persist until recovery phase has started?
Tubular cells are considered to be stable cells, meaning they can reenter the cell cycle and regenerate. This usually will take 2-3 weeks, thus patient can have continuing oliguria until enough cells have regenerated.