Renal Pathology Practice Questions

Q: Histologic sections of a kidney reveal patchy necrosis of epithelial cells of both the proximal and distal tubules with flattening of the epithelial cells, rupture of the basement membrane (tubulorrhexis), and marked interstitial edema. Acute inflammatory cells are not seen. What is the best diagnosis?

Acute tubular necrosis. ### Explanation **Correct Answer: B. Acute Tubular Necrosis (ATN)** **Why it is correct:** Acute Tubular Necrosis (ATN) is the most common cause of acute kidney injury (AKI) in hospitalized patients. The histological hallmark of ATN is the destruction of tubular epithelial cells [1]. This case describes **Ischemic ATN**, characterized by: 1. **Patchy involvement:** Unlike toxic ATN (which is continuous), ischemic ATN affects segments of both proximal and distal tubules [1]. 2. **Tubulorrhexis:** The rupture of the tubular basement membrane is a classic feature of ischemic injury [1]. 3. **Morphology:** Flattening of epithelial cells (regeneration) and interstitial edema are common [1]. The absence of acute inflammatory cells (neutrophils) helps distinguish this from an infectious process. **Why the other options are incorrect:** * **A & D. Pyelonephritis:** Acute pyelonephritis is characterized by **neutrophilic infiltration** (microabscesses) and white cell casts. Chronic pyelonephritis shows "thyroidization" of tubules and significant interstitial fibrosis. * **C. Chronic Glomerulonephritis:** This represents the end-stage of various glomerular diseases, characterized by hyalinized (sclerosed) glomeruli and global scarring, rather than acute tubular destruction. **NEET-PG High-Yield Pearls:** * **Ischemic ATN:** Patchy necrosis + Tubulorrhexis + Granular "Muddy Brown" casts in urine [1]. * **Toxic ATN:** Continuous necrosis (most prominent in the Proximal Convoluted Tubule) + Basement membrane usually remains intact. Common triggers: Gentamicin, Contrast dye, Myoglobin. * **Vulnerable Segments:** The Straight part of the Proximal Tubule (PST) and the Thick Ascending Limb (mTAL) are most susceptible to ischemia due to high metabolic activity [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 933-934.

Q: Diffuse proliferative glomerulonephritis in lupus nephritis falls under which class?

Class IV. **Explanation:** The International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification of Lupus Nephritis (LN) is a high-yield topic for NEET-PG. **Correct Option (C): Class IV – Diffuse Proliferative Lupus Nephritis (DPGN)** Class IV is the most common and most severe form of lupus nephritis [1]. It is defined by involvement of **≥50% of glomeruli**. Pathologically, it presents with endocapillary proliferation, "wire-loop" lesions (subendothelial deposits), and hyaline thrombi [1]. It carries the worst prognosis if untreated and often presents with nephritic syndrome and declining renal function. **Incorrect Options:** * **Class II (Mesangial Proliferative LN):** Characterized by purely mesangial hypercellularity and matrix expansion with mesangial immune deposits. It has a good prognosis. * **Class III (Focal Proliferative LN):** Similar to Class IV but involves **<50% of glomeruli** [1]. It is essentially a less extensive version of DPGN. * **Class V (Membranous LN):** Characterized by diffuse thickening of the glomerular basement membrane due to subepithelial deposits. It typically presents with nephrotic-range proteinuria. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most Common Class:** Class IV (Diffuse Proliferative) [1]. 2. **Most Common Cause of Death in SLE:** Renal failure (specifically Class IV). 3. **Wire-loop lesions:** Characteristic of Class IV (due to massive subendothelial deposits) [1]. 4. **Full House Pattern:** On Immunofluorescence (IF), there is positivity for IgG, IgA, IgM, C3, and C1q. 5. **Class VI:** Advanced Sclerotic LN (>90% globally sclerosed glomeruli; end-stage). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 230-232.

Question 1

Electron microscopy findings of renal biopsy shows permeation of the lamina densa of the glomerular basement membrane (GBM) by a ribbon-like, homogeneous, extremely electron-dense material of unknown composition. Which of the following is the likely diagnosis?

Accepted Answer

Dense-deposit disease (DDD)

Answer

Collapsing glomerulopathy

Answer

Minimal change disease

Answer

Focal segmental glomerulosclerosis (FSGS)

Question 2

Presence of islands of undifferentiated mesenchyme, often with cartilage, and immature collecting ducts on light microscopy will be seen in which cystic disease of the kidney?

Accepted Answer

Multicystic renal dysplasia

Answer

Medullary sponge kidney

Answer

Autosomal recessive polycystic kidney disease (ARPKD)

Answer

Autosomal dominant polycystic kidney disease (ADPKD)

Question 3

Which of the following is NOT a cause of acute tubulointerstitial nephritis?

Accepted Answer

Down's syndrome

Answer

Methicillin

Answer

Sjogren syndrome

Answer

Systemic Lupus Erythematosus (SLE)

Question 4

Which of the following is NOT a cystic disease of the kidney?

Accepted Answer

Horseshoe kidney

Answer

Medullary sponge kidney

Answer

Nephrophthisis

Answer

Glomerulocystic disease

Question 5

In which class of lupus nephritis is thrombosis most commonly seen?

Accepted Answer

Class III

Answer

Class I

Answer

Class II

Answer

Class IV

Question 6

Which of the following renal pathologies is present in a child who developed nephrotic syndrome after hepatitis B infection?

Accepted Answer

Membranous nephropathy

Answer

Focal segmental glomerulosclerosis

Answer

IgA nephropathy

Answer

Membranoproliferative glomerulonephritis

Question 7

Cylindrical dilatation of renal tubules is seen in?

Accepted Answer

Polycystic disease of kidney

Answer

Medullary cystic disease

Answer

Wilms tumour

Answer

Lipoid nephrosis

Question 8

Histologic sections of a kidney reveal patchy necrosis of epithelial cells of both the proximal and distal tubules with flattening of the epithelial cells, rupture of the basement membrane (tubulorrhexis), and marked interstitial edema. Acute inflammatory cells are not seen. What is the best diagnosis?

Accepted Answer

Acute tubular necrosis

Answer

Acute pyelonephritis

Answer

Chronic glomerulonephritis

Answer

Chronic pyelonephritis

Question 9

Which of the following drugs is a common cause of drug-induced interstitial nephritis?

Accepted Answer

Methicillin

Answer

Cloxacillin

Answer

Azlocillin

Answer

Piperacillin

Question 10

Diffuse proliferative glomerulonephritis in lupus nephritis falls under which class?

Accepted Answer

Class IV

Answer

Class II

Answer

Class III

Answer

Class V

Renal Pathology — MCQs

Renal Pathology — MCQs

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