Renal Pathology Practice Questions

Q: Hyaline casts are seen in which of the following conditions?

Normal urine. **Explanation:** **Hyaline casts** are the most common type of urinary cast. They are composed primarily of **Tamm-Horsfall mucoprotein** (uromodulin) secreted by the thick ascending limb of the Loop of Henle. Because they lack cellular inclusions, they appear transparent and colorless under light microscopy. 1. **Why "Normal urine" is correct:** Hyaline casts are not inherently pathological. They can be seen in healthy individuals, particularly following **strenuous exercise, dehydration**, or concentrated urine [1]. While they can increase in various renal diseases, their presence alone does not signify a specific pathology. 2. **Why the other options are incorrect:** * **Acute Tubular Necrosis (ATN):** Characterized by **"Muddy brown" granular casts** or renal tubular epithelial cell casts due to sloughing of necrotic cells. * **Thrombotic Microangiopathy (TMA):** Typically presents with hematuria and proteinuria; however, the hallmark is microangiopathic hemolytic anemia (schistocytes on smear). It does not produce specific diagnostic casts like hyaline casts. * **Pyelonephritis:** Characterized by **WBC (Leukocyte) casts**, which indicate tubulointerstitial inflammation or infection. **High-Yield Clinical Pearls for NEET-PG:** * **RBC Casts:** Pathognomonic for Glomerulonephritis (e.g., Post-streptococcal GN). * **WBC Casts:** Seen in Pyelonephritis and Acute Interstitial Nephritis (AIN). * **Fatty Casts ("Maltese Cross"):** Seen in Nephrotic Syndrome. * **Broad/Waxy Casts:** Indicative of Chronic Renal Failure (due to compensatory dilation of surviving nephrons). * **Granular Casts:** Often described as "weathered" cellular casts; seen in ATN (Muddy brown).

Q: Examine the renal histopathology slide. What is the probable diagnosis?

Post-streptococcal glomerulonephritis. ***Post-streptococcal glomerulonephritis*** - Characterized by **diffuse endocapillary hypercellularity** with **neutrophil infiltration** and enlarged, hypercellular glomeruli on light microscopy. - Electron microscopy shows pathognomonic **subepithelial electron-dense deposits** (humps), and immunofluorescence reveals a **starry sky pattern** with granular C3 and IgG deposits. *Membranoproliferative GN* - Shows **mesangial proliferation** with **double contour** appearance of glomerular basement membrane on light microscopy. - Electron microscopy reveals **subendothelial deposits** and **mesangial interposition**, not subepithelial humps. *Rapidly progressive GN* - Histologically characterized by **crescents** (>50% of glomeruli) composed of proliferating **epithelial cells** and **macrophages**. - Shows **necrotizing glomerulonephritis** with **fibrinoid necrosis** and **segmental sclerosis**, not endocapillary hypercellularity. *Diabetic nephropathy* - Light microscopy shows **nodular glomerulosclerosis** (Kimmelstiel-Wilson nodules) and **diffuse mesangial expansion**. - Electron microscopy reveals **thickened glomerular basement membrane** and **mesangial matrix expansion**, without immune deposits.

Q: The disease process that best accounts for this problem?

Vomiting. ***Vomiting*** - Can cause **Mallory-Weiss tears** in the esophagus due to sudden increase in intragastric pressure during forceful retching. - May lead to **hypokalemic vacuolar nephropathy** from electrolyte losses, causing characteristic **vacuolar changes** in renal tubular epithelium. *Ethylene glycol poisoning* - Causes **oxalate crystal nephropathy** with pathognomonic **calcium oxalate crystals** in renal tubules and interstitium. - Results in **acute tubular necrosis** and **metabolic acidosis** with anion gap, not the pathological changes described. *Chronic obstructive pulmonary disease* - Characterized by **emphysema** (alveolar destruction) and **chronic bronchitis** (mucus gland hyperplasia). - Primarily affects the **respiratory system** with **air trapping** and **hyperinflation**, not the pathological process in question. *Congestive heart failure* - Causes **pulmonary congestion** with **hemosiderin-laden macrophages** (heart failure cells) in lungs. - Results in **cardiac cachexia** and **hepatic congestion** with **nutmeg liver** pattern, distinct from the described pathology.

Q: Hobnail pattern is seen in which type of Renal Cell Carcinoma?

Collecting duct. **Explanation:** The **Collecting Duct Carcinoma (CDC)**, also known as Bellini duct carcinoma, is a rare but highly aggressive subtype of Renal Cell Carcinoma (RCC) arising from the distal segment of the collecting ducts. **Why the correct answer is right:** The characteristic histological feature of CDC is a **tubulopapillary architecture** lined by highly atypical cells. These cells exhibit a **"Hobnail appearance,"** where the nuclei bulge into the lumen of the tubules or papillae due to a high nuclear-to-cytoplasmic ratio and apical displacement. This pattern is a classic morphologic hallmark used to differentiate it from other renal tumors. **Why the incorrect options are wrong:** * **Clear cell RCC:** The most common type; characterized by cells with clear cytoplasm (due to glycogen and lipid) and a prominent delicate vascular network ("chicken-wire" pattern) [1]. * **Papillary RCC:** Characterized by papillae with fibrovascular cores containing **foamy macrophages** and psammoma bodies [1]. * **Chromophobe RCC:** Features large polygonal cells with prominent cell membranes (**"vegetable cell" appearance**), perinuclear halos, and "raisinoid" nuclei [1]. It stains positive with **Hale’s Colloidal Iron**. **High-Yield Clinical Pearls for NEET-PG:** * **Origin:** Medulla (unlike Clear cell/Papillary which arise from the Proximal Convoluted Tubule). * **Prognosis:** Extremely poor; most patients present with metastatic disease. * **Immunohistochemistry:** CDC is often positive for **High Molecular Weight Cytokeratin (HMWK)** and Ulex europaeus agglutinin-1 (UEA-1). * **Differential Diagnosis:** Medullary carcinoma (associated with Sickle Cell Trait) also shows hobnailing but is distinguished by its association with hemoglobinopathies. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 959-961.

Q: Which chromosome is involved in Wilm's tumor?

11. **Explanation:** **Wilms Tumor (Nephroblastoma)** is the most common primary renal malignancy in children. The correct answer is **Chromosome 11** because the pathogenesis of Wilms tumor is primarily linked to mutations or deletions in tumor suppressor genes located on this chromosome. * **WT1 Gene (11p13):** Associated with WAGR syndrome and Denys-Drash syndrome. * **WT2 Gene (11p15):** Associated with Beckwith-Wiedemann syndrome. **Analysis of Incorrect Options:** * **Option B (Chromosome 13):** This is the location of the **RB1 gene**. Mutations here are associated with **Retinoblastoma** and Osteosarcoma. * **Option C (Chromosome 18):** Associated with **Edwards Syndrome** (Trisomy 18). While children with certain trisomies have increased cancer risks, it is not the primary locus for Wilms tumor. * **Option D (Chromosome 22):** This is the location of the **NF2 gene** (Neurofibromatosis type 2) and the **SMARCB1 gene** (associated with Malignant Rhabdoid Tumor of the kidney, which is a distinct entity from Wilms tumor). **High-Yield Clinical Pearls for NEET-PG:** 1. **WAGR Syndrome:** **W**ilms tumor, **A**niridia, **G**enitourinary anomalies, and mental **R**etardation (Deletion of 11p13). 2. **Beckwith-Wiedemann Syndrome:** Macroglossia, Organomegaly, Hemi-hypertrophy, and Omphalocele (11p15). 3. **Classic Presentation:** A painless, palpable abdominal mass in a child (usually 2–5 years old) that **does not cross the midline** (unlike Neuroblastoma). 4. **Histology:** Characterized by a **triphasic pattern** (blastemal, stromal, and epithelial cells). 5. **Most common site of metastasis:** Lungs ("Cannon-ball" appearance on X-ray).

Q: Which of the following is a feature of autosomal recessive polycystic kidney disease?

Can be diagnosed intrauterine. **Explanation:** **Autosomal Recessive Polycystic Kidney Disease (ARPKD)** is a genetic disorder caused by mutations in the **PKHD1 gene** on chromosome 6, which encodes **fibrocystin** [1]. 1. **Why Option A is correct:** ARPKD can be diagnosed **intrauterine** via prenatal ultrasound. Characteristic findings include bilaterally enlarged, echogenic kidneys and **oligohydramnios** (due to poor fetal urine output). Severe cases present at birth (Potter sequence) with pulmonary hypoplasia [1]. 2. **Why other options are incorrect:** * **Option B:** While some patients survive to school age, the classic "infantile" form often leads to **perinatal or neonatal death** due to respiratory failure [1]. It does not "progress" to failure by school age; rather, those who survive birth usually already have significant renal impairment. * **Option C:** While the kidneys are massively enlarged, they are typically described as **smooth and symmetrical** (due to small, radially arranged cortical cysts), unlike the "bosselated" or "knobby" irregular masses palpated in Autosomal Dominant PKD (ADPKD). * **Option D:** Hypertension is a **very early and severe** feature of ARPKD, often appearing in the neonatal period, and is a major cause of morbidity. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** Characterized by **cylindrical/saccular dilation of collecting ducts** (radial arrangement) [1]. * **Liver Involvement:** 100% of cases have **Congenital Hepatic Fibrosis**. If the patient survives the renal complications, they often present later with portal hypertension and splenomegaly. * **Potter Sequence:** Oligohydramnios → Fetal compression → Clubbed feet, flattened facies, and pulmonary hypoplasia. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 952-953.

Q: Chronic urethral obstruction due to benign prostatic hyperplasia can lead to which change in the kidney parenchyma?

Atrophy. **Explanation:** The correct answer is **Atrophy**. **Mechanism:** Chronic urethral obstruction due to Benign Prostatic Hyperplasia (BPH) leads to a retrograde increase in pressure. This pressure is transmitted from the bladder through the ureters (hydroureter) to the renal pelvis and calyces (**Hydronephrosis**). The persistent mechanical pressure on the renal papillae and parenchyma, combined with compression of the renal vasculature (leading to ischemia), results in the progressive loss of nephrons and thinning of the renal cortex and medulla. This process is specifically termed **Pressure Atrophy**. **Why other options are incorrect:** * **Hyperplasia:** This involves an increase in the *number* of cells. While the prostate undergoes hyperplasia in BPH, the kidney does not respond to pressure by increasing cell numbers. * **Hypertrophy:** This is an increase in the *size* of cells. While the bladder wall may undergo compensatory hypertrophy to overcome obstruction, the kidney parenchyma undergoes destruction and shrinkage rather than growth. * **Dysplasia:** This refers to disordered growth and maturation of an epithelium (often pre-neoplastic) or abnormal organ development (e.g., Multicystic Dysplastic Kidney). It is not a secondary response to mechanical obstruction in adults. **Clinical Pearls for NEET-PG:** * **Bladder Changes in BPH:** Initial response is **Hypertrophy** of the detrusor muscle, leading to **trabeculation** and **diverticula** formation. * **Post-renal Azotemia:** Chronic bilateral obstruction can lead to chronic kidney disease (CKD). * **Key Histology:** Pressure atrophy in the kidney is characterized by glomerular hyalinization and tubular atrophy (often appearing as "thyroidization" of the kidney).

Q: A patient with renal disease undergoes a biopsy. On Congo red staining, the deposits show apple-green birefringence under polarised light. What is the most likely diagnosis?

Amyloidosis. ***Amyloidosis***- This feature is the **pathognomonic microscopic manifestation** of amyloid deposition, where the Congo red stain binds specifically to the parallel **cross-beta sheet** configuration of amyloid fibrils [1].- When viewed under **polarized light**, this interaction results in the classic **apple-green birefringence** due to the ordering of the deposited protein [1], [2]. *Minimal change disease*- The diagnosis of minimal change disease relies primarily on **electron microscopy**, which shows **effacement of podocyte foot processes**.- On **light microscopy**, the glomeruli appear virtually normal, and there are no deposits present that would stain positively with Congo red. *Diabetic nephropathy*- Characteristic findings on light microscopy include **diffuse mesangial expansion** and the formation of **Kimmelstiel-Wilson nodules** (nodular glomerulosclerosis).- The thickening of the glomerular basement membrane and mesangial expansion are due to hyperglycemia and associated metabolic changes, not amyloid deposition. *Membranous nephropathy*- This nephropathy is defined by the presence of **subepithelial immune complex deposits** that result in a uniformly thickened glomerular basement membrane (GBM).- Silver stains often reveal a classic **"spike and dome"** pattern on the GBM, which is distinct from amyloid fibrils. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 268-269. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 533-534.

Question 1

Glomerulonephritis is due to what mechanism?

Accepted Answer

Immune complex deposition

Answer

Type I hypersensitivity reaction

Answer

Type IV hypersensitivity reaction

Answer

Type V hypersensitivity reaction

Question 2

Hyaline casts are seen in which of the following conditions?

Accepted Answer

Normal urine

Answer

Acute tubular necrosis

Answer

Thrombotic microangiopathy

Answer

Pyelonephritis

Question 3

Examine the renal histopathology slide. What is the probable diagnosis?

Accepted Answer

Post-streptococcal glomerulonephritis

Answer

Membranoproliferative GN

Answer

Rapidly progressive GN

Answer

Diabetic nephropathy

Question 4

The disease process that best accounts for this problem?

Accepted Answer

Vomiting

Answer

Ethylene glycol poisoning

Answer

Chronic obstructive pulmonary disease

Answer

Congestive heart failure

Question 5

Hobnail pattern is seen in which type of Renal Cell Carcinoma?

Accepted Answer

Collecting duct

Answer

Clear cell

Answer

Papillary

Answer

Chromophobe

Question 6

Type I RPGN is seen in which of the following conditions?

Accepted Answer

Goodpasture's syndrome

Answer

Cryoglobulinemia

Answer

SLE

Answer

Wegner's granulomatosis

Question 7

Which chromosome is involved in Wilm's tumor?

Accepted Answer

11

Answer

13

Answer

18

Answer

22

Question 8

Which of the following is a feature of autosomal recessive polycystic kidney disease?

Accepted Answer

Can be diagnosed intrauterine

Answer

Progresses to renal failure by school age

Answer

Can be palpated abdominally

Answer

Hypertension does not develop until late stages of the disease

Question 9

Chronic urethral obstruction due to benign prostatic hyperplasia can lead to which change in the kidney parenchyma?

Accepted Answer

Atrophy

Answer

Hyperplasia

Answer

Hypertrophy

Answer

Dysplasia

Question 10

A patient with renal disease undergoes a biopsy. On Congo red staining, the deposits show apple-green birefringence under polarised light. What is the most likely diagnosis?

Accepted Answer

Amyloidosis

Answer

Diabetic nephropathy

Answer

Membranous nephropathy

Answer

Minimal change disease

Renal Pathology — MCQs

Renal Pathology — MCQs

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