Thrombotic thrombocytopenic purpura is a syndrome characterized by which of the following?

Thrombocytopenia, anemia, neurological abnormalities, progressive renal failure and fever

Thrombocytopenia, anemia, neurological abnormalities, progressive hepatic failure and fever

Thrombocytopenia, normal anemia, neurological abnormalities, progressive renal failure and fever

Thrombocytopenia, anemia, no neurological abnormalities, progressive renal failure and fever

IgA nephropathy is not associated with which of the following?

Gross hematuria concurrent with upper respiratory infection

Immunofluorescence deposits contain IgA and IgG

A 7 year old boy presented with generalized edema. Urine examination revealed marked albuminuria. Serum biochemical examinations showed hypoalbuminemia with hyperlipidemia. Kidney biopsy was undertaken. On light microscopic examination, the kidney appeared normal. Electron microscopic examination is most likely to reveal

Fusion of foot processes of the glomerular epithelial cells

Rarefaction of glomerular basement membrane

Deposition of electron dense material in the basement membrane

Vascular Diseases of the Kidney for INI-CET: High-Yield Pathology Lessons

Hypertensive Nephropathy - Pressure Problems

Benign Nephrosclerosis: Chronic, mild-moderate hypertension.
- Pathology: Hyaline arteriolosclerosis (thickened arteriolar walls, narrowed lumen).
- Gross: Symmetrically atrophic kidneys, finely granular cortical surface ('granular contracted kidneys').
- Clinical: Slow, progressive renal insufficiency.
Malignant (Accelerated) Nephrosclerosis: Severe, rapidly rising BP (often >180/120 mmHg).
- Pathology:
  - Fibrinoid necrosis of arterioles (smudgy, eosinophilic deposits).
  - Hyperplastic arteriolosclerosis ('onion-skinning' due to concentric smooth muscle cell proliferation & collagen deposition).
- Gross: Normal size or slightly enlarged kidneys; petechial hemorrhages on cortical surface ('flea-bitten' kidney).
- Clinical: Acute renal failure, papilledema, hypertensive encephalopathy, headaches, visual disturbances.

⭐ 'Onion-skin' appearance of arterioles is pathognomonic for malignant hypertension.

📌 Mnemonic: Benign = Boringly slow, hyaline. Malignant = Madly fast, fibrinoid & onion skinning, Many petechiae (flea-bitten).

Renal Artery Stenosis - Pipe Dreams

Causes
- Atherosclerosis: Most common; elderly males, ostial.
- Fibromuscular Dysplasia (FMD): Young females; 'string of beads'. 📌 FMD - 'Females, Medial, Dysplasia'.
Pathophysiology: ↓ Renal Perfusion → RAAS activation → Renovascular HTN.

Clinical Features
- Refractory HTN (>70% stenosis).
- Abdominal bruit.
- Flash pulmonary edema.
- AKI on ACEi/ARB.
Diagnosis
- Doppler US: Initial.
- CTA / MRA.
- DSA: Gold standard.

Renal artery fibromuscular dysplasia "string of beads" Renal artery angiogram: Normal vs. fibromuscular dysplasia

⭐ Unexplained hypokalemia can be a clue for Renal Artery Stenosis due to secondary hyperaldosteronism.

Thrombotic Microangiopathies - Clot Chaos

Pathophysiology: Endothelial injury → platelet activation → microvascular thrombi.
Hallmarks: Microangiopathic Hemolytic Anemia (MAHA), thrombocytopenia, organ damage (kidney, CNS).

Feature	Hemolytic Uremic Syndrome (HUS)	Thrombotic Thrombocytopenic Purpura (TTP)
Etiology	Typical (D+): Shiga toxin (E.coli O157:H7)	Acquired: Anti-ADAMTS13 Abs
	Atypical (D-): Complement dysregulation	Hereditary: ADAMTS13 mutations. Activity <10%
Key Features	Predominant acute renal failure (children)	Predominant neurological symptoms, fever (adults)
Lab Findings	MAHA, thrombocytopenia, schistocytes, ↑ creatinine	MAHA, thrombocytopenia, schistocytes, severe ADAMTS13 deficiency
Organ Inv.	Kidney (severe) >> CNS	CNS (prominent), Kidney (milder)

Peripheral blood smear with schistocytes Fibrin thrombi at vascular pole in kidney biopsy

⭐ Presence of schistocytes on peripheral blood smear is a hallmark of thrombotic microangiopathies.

Emboli & Infarcts - Vascular Blockades

Atheroembolic Renal Disease (AERD):
- Cause: Cholesterol crystal emboli, typically after invasive arterial procedures (e.g., angiography).
- Clinical: Subacute renal failure (↑creatinine), eosinophilia, livedo reticularis, purple toes, ↓complement.
- Patho: Biconvex, needle-shaped cholesterol crystal clefts in small renal vessels.
Renal Infarction:
- Etiology: Thromboembolism (e.g., AF, endocarditis, mural thrombi); also trauma, vasculitis (PAN).
- Gross: Wedge-shaped pale cortical necrosis. Old infarcts: shrunken, fibrotic.
- Features: Acute flank pain, hematuria, fever, nausea, markedly ↑LDH.

⭐ Atheroembolic renal disease often presents with a subacute rise in creatinine, eosinophilia, and low complement levels after an invasive vascular procedure.

High‑Yield Points - ⚡ Biggest Takeaways

Renal Artery Stenosis (RAS): Key cause of secondary HTN; atherosclerosis (elderly), fibromuscular dysplasia (young women).

Malignant Hypertension: Fibrinoid necrosis, hyperplastic arteriolosclerosis ("onion-skin"), "flea-bitten" kidney. Benign: hyaline arteriolosclerosis.

Thrombotic Microangiopathies (TMAs): HUS (Shiga toxin, child, renal failure) vs. TTP (ADAMTS13, adult, neuro).

Renal Infarcts: Wedge-shaped cortical necrosis, usually embolic.

Atheroembolic Disease: Cholesterol crystals post-procedure; eosinophilia, livedo reticularis.

Scleroderma Renal Crisis: Abrupt severe HTN & AKI.

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