9/22- Cases: Diabetic NP, Focal Segmental Glomerulonephritis, and Malignant HTN Flashcards Preview

MS2 Renal > 9/22- Cases: Diabetic NP, Focal Segmental Glomerulonephritis, and Malignant HTN > Flashcards

Flashcards in 9/22- Cases: Diabetic NP, Focal Segmental Glomerulonephritis, and Malignant HTN Deck (29)


- A 54 year-old woman presented with peripheral edema

Laboratory tests:

- Serum creatinine of 1.8 mg/dl

- 24 hour protein excretion of 4.1 grams

- The serum creatinine was 1.5 mg/dl and the 24-hour protein excretion was 1.3 grams 6 months previously


- The patient had adult-onset diabetes diagnosed about 5 years ago. The diabetes was reported to be well controlled. There was no retinopathy

- Serologic tests for hepatitis C viral infection was positive; but other serologic tests were negative.

- A renal biopsy was performed.

What renal syndrome is this? Possible causes?

NEPHROTIC syndrome

- Proteinuria > 3.5 g/day

- Peripheral edema

Possible causes (in adults):

- Idiopathic focal segmental glomerulosclerosis

- Membranous glomerulopathy

- Diabetic nephropathy

- Amyloidosis


Why is renal biopsy needed in this pt?

Patient may have diabetic nephropathy or Hep C related glomerulonephritis

- Clinical features can't distinguish and treatments are very different


What do you see in this renal biopsy?

Diabetic nephropathy

- Glomerulus characterized by diffuse and nodular enlargement of mesangial areas

- There is diffuse and uniform thickening of the GBM, and thickening of tubular BM

- Some glomeruli are completely sclerosed

- This biopsy clearly shows features of diabetic nephropathy and rules out the possibility of Hepatitis C-related glomerulonephritis (see following images)


What is seen here?

Diabetic nephropathy

- A glomerulus with predominantly nodular mesangial enlargement (Kimmelstiel Wilson)


What is seen here?

Diabetic nephropathy:

- A glomerulus characterized by diffuse enlargement of mesangial areas

- There is also diffuse thickening of the glomerular basement membranes

- Arteriolar changes are also seen (*)


What is seen here?

Diabetic nephropathy

- Global glomerular sclerosis

- Thickening of the tubular basement membranes (arrows).


What do you see in EM in diabetic nephropathy?

Thickening of glomerular basement membranes and foot process effacement


How do the renal biopsy findings guide therapy?

What is the treatment for:

- Hep C related GN

- Diabetic nephropathy

- If the patient had Hepatitis C-related glomerulonephritis, antiviral therapy including alpha interferon is indicated.

- Treatment for diabetic nephropathy is quite different and includes control of diabetes, control of hypertension, and pharmacologic blocking of the renin-angiotensin system


Case 2)

- A 24 year-old woman presented to her primary care physician seeking referral to a bariatric surgeon for a gastric bypass procedure.

- Physical examination revealed a normotensive obese female (BMI 44) with acanthosis nigricans


- Abnormal lipid and liver function tests

- Serum creatinine was normal but urinalysis was abnormal with 2+ proteinuria and 24 hour protein excretion of 1.4 grams

- Liver biopsy findings were consistent with non-alcoholic steatohepatitis

- The renal biopsy findings are provided. 

What syndrome is this?

This is NOT nephrotic syndrome

- Proteinuria is under 3.5 g/day and no peripheral edema

Her “abnormal” lipid studies (likely elevated triglycerides and low HDL), skin findings, and liver biopsy results suggest metabolic syndrome (insulin resistance syndrome).


What is shown in this LM of renal biopsy in this (case 2) pt? 

- Glomerular enlargement (compare the diameters of both glomeruli)

- Tubules and vessels appear normal here (H&E stain)


What is seen here? 

Focal Segmental Glomerulosclerosis

- Size variation persists but there are also segmental regions of tuft agglutination or scarring (*)

- Tubules and vessels still appear normal (PAS stain)


What is seen here? 

Focal Segmental Glomerulosclerosis

- Segmental sclerosis (*)

- Focal tubular atrophy (arrow) with normal vessel. (PAS stain)


What is seen here? 

- In addition to segmental regions of tuft agglutination or scarring (*) there are now collections of atrophic tubules (arrow). (PAS stain)


What is more predictive of ESRF: glomeruli or tubule damage?



What is seen in EM of renal biopsy in Focal Segmental Glomerulosclerosis? What does this signify?

- Visceral epithelial cell foot processes are preserved in this case (big dense dark spots are RBCs here)

- This suggests the injury is a secondary FSGS rather than primary or idiopathic FSGS (which can also present as asymptomatic proteinuria)

Treatment varies between the two types.


What are the two types of FSGS?

1. Primary/Idiopathic

2. Secondary FSGS


What is the proposed pathogenesis of secondary FSGS?

"Adaptive" or "hyper-filtering" FSGS

- In obesity there is increased glomerular perfusion and filtration with increased glomerular pressure leading to stretching of the capillary wall and injury to all glomerular compartments

- Endocrine changes (RAS, insulin induced growth factors) also contribute.

- The most common cause of secondary FSGS is obesity (sometimes called obesity related glomerulopathy or nephropathy).


What are 3 other scenarios (non obesity/diabetes) that may result in diagnosis of secondary FSGS?

1. Decreased nephron mass due to surgical resections (such as prior nephrectomy for cancer)

2. Impaired nephron development (such as pre-term or low birthweight infants)

3. Progressive impairment due to prior glomerular injury ( such as prior injury from glomerulonephritis)


Case 3)

- 65 year-old woman presented to the ER with abdominal pain and vomiting for several months

- In the ER she becomes lethargic and unresponsive

- Her examination is significant for a blood pressure of 270/170 mmHg


- BUN 82 and Cr 5.7 mg/dL.

- Urinalysis contains 4+ protein and blood.

- The patient is anemic and thrombocytopenic with a normal ADAMTS13 level

. - EKG changes were consistent with chronic hypertension.

Per family members the patient has had high blood pressure for a long time but isn’t on any anti-hypertensive medications.

- Proteinuria was found one year ago at an ER visit but she had no further work up.

- A renal biopsy was performed

What renal syndrome is this? Possible causes?

Acute renal failure

- It is important to recognize that before the development of acute renal failure, there were already baseline renal abnormalities (previous history of proteinuria) probably related to an underlying hypertensive nephrosclerosis (EKG changes, history of long standing untreated hypertension).

- Acute renal failure developed from the background of impaired renal function in this patient (acute on chronic renal failure)

Possible causes of ARF may be pre-renal, renal, or post-renal

- Renal causes: mainly related to severe involvement of one of the 3 main renal compartments (i.e. glomerular, tubulointerstitial, or vascular)

- Other diseases can present with neurologic changes, renal failure, anemia, and thrombocytopenia (including HUS and TTP)


What does this renal biopsy show?

(Inset = normal)

- Vascular changes consistent with malignant hypertension: thrombosed and thickened vessels; chronic changes (no blood flow)

- The background kidney is end-stage

- The etiology of the chronic renal injury is unclear but may be related to untreated chronic hypertension

- The kidney is too far gone at this point to identify the etiology of underlying renal disease, though no immune complexes were identified (see following images).


What is seen here? 

- Tortuous arteriole with intimal thickening and pink smudging of vessel wall (arrows) characteristic of fibrinoid necrosis.

- Fibrinoid is red on trichrome staining (green background

- Green = collagen; fibrin = red


What is seen here?

An arteriole showing fibrin thrombus (t) and marked intimal thickening (i). A barely discernible sclerotic glomerulus (G) is present.

- Hot pink = thrombus


What is seen here?

Involuting glomerular tuft with tubular atrophy and interstitial fibrosis (long standing chronic renal disease). Thrombosed arterioles (arrow).


What is seen here? 

Shriveled glomerular tuft with wrinkled GBMs and areas of reduplication (arrow)

- Can see "tram-tracking": black depositions running side by side (something is splitting the membrane)


What is seen here? 

Electron microscopy shows subendothelial electron lucent areas (**)

- "subendothelial lucency"- seen in microangiopathic disease (?)

- RBCs stuck outside the lumen


What is seen here? 

Electron microscopy shows subendothelial electron lucent areas (**).

Trapped red blood cells (*) contribute to schistocytes and hemolysis seen in thrombotic microangiopathies. No immune deposits.


Based on the previous pictures, what is the diagnosis?

Malignant nephrosclerosis in a background of chronic renal disease


What is the underlying disease process in malignant nephrosclerosis and how does it happen?

- Malignant hypertension may be primary (previously normal blood pressure) or secondary (chronic hypertension)

- The high pressure injures the endothelium of the vessels, forcing plasma proteins into the vessel wall and activating the coagulation cascade resulting in thrombosis

- Most patients have underlying severe renal disease, as is this case

- Malignant hypertension must be distinguished clinically from other thrombotic microangiopathies including hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP)

- The renal biopsy findings may be similar in all thrombotic microangiopathies

- In this case the ADAMTS13 level was normal, excluding TTP.


What is the renal outcome of this patient?

- 1 year survival for untreated malignant hypertension is roughly 10%.

- Intravenous antihypertensive medications must be administered to gradually lower the blood pressure. Mean arterial pressure must stay high because many vessels are narrowed. Dropping the blood pressure too much may lead to organ ischemia.

- The prognosis depends on the degree of underlying renal injury. Many patients develop end-stage renal disease, and become dialysis dependent, as did this patient.