Renal Pathology Practice Questions

Q: A specimen shows a nephrectomy. What is your diagnosis?

Renal cell carcinoma. ***Renal cell carcinoma*** - Presents as a **golden-yellow variegated** mass in the **renal cortex** with areas of **hemorrhage and necrosis** on gross examination. - Typically shows **clear cell morphology** with abundant cytoplasm and is the most common primary renal malignancy requiring nephrectomy. *Renal papillary adenoma* - Usually **very small** (typically <5mm) **benign tumors** that rarely require nephrectomy due to their minimal size. - Characterized by **papillary architecture** with **bland cytology** and lack the aggressive features seen in larger masses. *Urothelial cancer of renal pelvis* - Arises from the **renal pelvis** and **collecting system**, not the cortical parenchyma like RCC. - Shows **white-tan** appearance with **papillary or solid growth** pattern extending into the pelviocalyceal system. *Oncocytoma* - Appears as a **well-circumscribed tan-brown mass** with a characteristic **central stellate scar** on cut surface. - **Benign tumor** composed of **oncocytes** with abundant eosinophilic cytoplasm, typically doesn't require nephrectomy unless large.

Q: What is the most common renal tumour?

Renal cell carcinoma. **Explanation:** **Renal Cell Carcinoma (RCC)** is the most common primary malignancy of the kidney, accounting for approximately **80-85%** of all malignant renal tumors in adults [1]. It originates from the renal tubular epithelium, most commonly the proximal convoluted tubule (in the case of the Clear Cell subtype). **Analysis of Options:** * **A. Renal Cell Carcinoma (Correct):** It is the most frequent renal tumor in adults, typically occurring in the 6th to 7th decades of life. Risk factors include smoking, obesity, hypertension, and acquired cystic kidney disease (ACKD) in dialysis patients [1]. * **B. Wilm’s Tumour (Nephroblastoma):** While it is the most common renal tumor in **children** (typically aged 2–5 years), it is rare in adults. * **C & D. Squamous and Transitional Cell Carcinoma:** These arise from the **urothelium** of the renal pelvis, not the renal parenchyma. Transitional Cell Carcinoma (TCC) is the most common tumor of the renal pelvis, but it is significantly less common than RCC overall [1]. Squamous cell carcinoma is rare and usually associated with chronic irritation (e.g., staghorn calculi). **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Hematuria (most common), flank pain, and a palpable mass (seen in only 10% of cases). * **Most Common Subtype:** Clear Cell RCC (associated with **VHL gene** deletion on Chromosome 3p) [1]. * **Paraneoplastic Syndromes:** RCC is known as the "Internist's Tumor" because it can secrete hormones leading to Polycythemia (EPO), Hypercalcemia (PTHrP), and Hypertension (Renin). * **Staging:** The most important prognostic factor is the pathologic stage (TNM), specifically invasion of the renal vein or perinephric fat [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 958-961.

Q: Bilateral renal cell carcinoma is seen in which of the following conditions?

Von Hippel-Lindau disease. ### **Explanation** **Correct Option: C. Von Hippel-Lindau (VHL) disease** Von Hippel-Lindau disease is an autosomal dominant hereditary cancer syndrome caused by a mutation in the **VHL gene on chromosome 3p25**. The VHL protein normally degrades hypoxia-inducible factor (HIF); its loss leads to increased angiogenesis and cell proliferation. Approximately **25–45%** of patients with VHL develop **Clear Cell Renal Cell Carcinoma (RCC)**. A hallmark of hereditary RCC (like VHL) is that the tumors are frequently **bilateral and multicentric**, occurring at a younger age compared to sporadic cases [1]. **Analysis of Incorrect Options:** * **A. Eagle-Barrett Syndrome (Prune Belly Syndrome):** Characterized by a triad of abdominal muscle deficiency, undescended testes, and urinary tract abnormalities (e.g., megaureter). It is not associated with a predisposition to RCC. * **B. Beckwith-Wiedemann Syndrome:** A pediatric overgrowth disorder (WT2 mutation on Ch 11p15) associated with macroglossia, omphalocele, and hemihypertrophy. It significantly increases the risk of **Wilms tumor (Nephroblastoma)**, not RCC. * **D. Bilateral Angiomyolipoma:** While these are benign mesenchymal tumors frequently seen in **Tuberous Sclerosis** [1], they are not carcinomas. Although they can be bilateral, they do not represent Renal Cell Carcinoma. **High-Yield Clinical Pearls for NEET-PG:** * **VHL Syndrome Triad:** Hemangioblastomas (cerebellum/retina), Pheochromocytoma, and Clear Cell RCC. * **Most common type of RCC in VHL:** Clear Cell variant [1]. * **Other syndromes with RCC:** Hereditary Papillary Renal Carcinoma (MET gene) and Birt-Hogg-Dubé syndrome (FLCN gene - associated with chromophobe RCC) [1]. * **Staining:** RCC is typically positive for **Vimentin and CD10**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 957-961.

Q: All of the following are causes of acute tubular necrosis (ATN) except?

Placenta previa. Acute Tubular Necrosis (ATN) is the most common cause of intrinsic Acute Kidney Injury (AKI), resulting from either **prolonged ischemia** or **direct nephrotoxicity** [1]. **Why Placenta Previa is the correct answer:** Placenta previa refers to the implantation of the placenta over the internal os. While it causes significant painless antepartum hemorrhage, it is typically managed electively or diagnosed early. Unless it leads to massive, uncompensated hemorrhagic shock (which is rare with modern management), it does not characteristically cause ATN. In contrast, **Abruptio placentae** (Option D) is a classic cause of severe, sudden concealed or revealed hemorrhage leading to profound hypotension and is a notorious trigger for both ATN and **Bilateral Renal Cortical Necrosis**. **Analysis of Incorrect Options:** * **Radiocontrasts (Option A):** These are potent **nephrotoxins**. They cause ATN through a combination of direct tubular toxicity and intense intrarenal vasoconstriction (medullary hypoxia). * **Amphotericin B (Option B):** This antifungal is a well-known **nephrotoxin**. It causes ATN by increasing tubular permeability and inducing distal renal tubular acidosis (Type 1 RTA). * **Abruptio placentae (Option D):** As mentioned, this leads to severe **ischemic ATN** due to hypovolemic shock and is a high-yield obstetric cause of acute renal failure [1]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Urinary Findings in ATN:** Muddy brown granular casts are pathognomonic. 2. **Fractional Excretion of Sodium (FeNa):** Typically **>2%** in ATN (distinguishes it from Pre-renal AKI where FeNa is <1%). 3. **Ischemic vs. Toxic ATN:** Ischemic ATN primarily affects the **S3 segment** of the proximal tubule and the thick ascending limb of Henle, whereas toxic ATN primarily affects the **S1 and S2 segments** of the proximal tubule.

Q: All of the following are true about thin basement membrane defect, except:

Impaired renal function. **Explanation:** **Thin Basement Membrane Disease (TBMD)**, also known as **Benign Familial Hematuria**, is a common hereditary glomerular disease. The correct answer is **D** because TBMD is characterized by an excellent prognosis with **preserved renal function**; progression to chronic kidney disease or renal failure is extremely rare. * **Why Option D is correct:** Unlike Alport Syndrome, TBMD does not typically lead to hypertension, significant proteinuria, or impaired renal function. The glomerular filtration rate (GFR) remains normal throughout life. * **Why Option A is wrong:** TBMD is synonymous with "Benign Familial Hematuria" because of its non-progressive nature and strong familial tendency. * **Why Option B is wrong:** The inheritance pattern is typically **Autosomal Dominant**. It most commonly results from heterozygous mutations in the *COL4A3* or *COL4A4* genes (the same genes involved in Alport Syndrome). * **Why Option C is wrong:** The hallmark clinical presentation is persistent or recurrent **microscopic hematuria**, often discovered incidentally during routine urinalysis in childhood or young adulthood. **High-Yield Clinical Pearls for NEET-PG:** * **Electron Microscopy (EM):** This is the gold standard for diagnosis. It shows diffuse thinning of the Glomerular Basement Membrane (GBM), often measuring **150–250 nm** (Normal is ~300–400 nm). * **Light Microscopy & Immunofluorescence:** Usually appear completely **normal**. * **Differential Diagnosis:** It must be distinguished from **Alport Syndrome**, which presents with a "basket-weave" appearance on EM, sensorineural deafness, ocular defects, and progressive renal failure. * **Key Distinction:** TBMD = Heterozygous mutation; Alport Syndrome = X-linked (most common) or Autosomal Recessive (homozygous/compound heterozygous).

Q: Which chromosomes are involved in adult polycystic kidney disease (APKD)?

4 and 16. **Explanation:** Autosomal Dominant Polycystic Kidney Disease (ADPKD), often referred to as adult polycystic kidney disease, is a multisystemic genetic disorder characterized by the progressive formation of fluid-filled cysts in the renal parenchyma [1]. **Why Option B is correct:** ADPKD is primarily caused by mutations in two specific genes: 1. **PKD1 Gene:** Located on **Chromosome 16p13.3**. It encodes the protein **Polycystin-1**. This mutation accounts for approximately **85%** of cases and is associated with a more severe phenotype and earlier progression to End-Stage Renal Disease (ESRD) (mean age ~54 years) [1]. 2. **PKD2 Gene:** Located on **Chromosome 4q21**. It encodes **Polycystin-2**. This mutation accounts for roughly **15%** of cases and generally presents with a milder clinical course and later onset of ESRD (mean age ~74 years) [1]. **Why other options are incorrect:** * **Options A, C, and D:** While Chromosome 4 is correctly associated with the PKD2 gene, chromosomes 11, 12, and 17 do not harbor the primary genes responsible for ADPKD. (Note: Chromosome 6 is associated with Autosomal Recessive PKD/ARPKD via the PKHD1 gene). **High-Yield Clinical Pearls for NEET-PG:** * **Extra-renal manifestations:** The most common is **Liver cysts**. The most life-threatening is **Berry Aneurysms** (Circle of Willis), which can lead to Subarachnoid Hemorrhage (SAH). Other features include Mitral Valve Prolapse (MVP) and diverticulosis. * **Diagnosis:** Ultrasonography is the first-line screening tool (Ravine’s criteria). * **Management:** Tolvaptan (Vasopressin V2 receptor antagonist) is used to slow cyst growth and disease progression.

Q: Staghorn calculus is primarily composed of which substance?

Magnesium ammonium phosphate. **Explanation:** **Staghorn calculus** (also known as a triple phosphate or struvite stone) is a large, branching stone that occupies the renal pelvis and extends into at least two calyces, resembling the antlers of a stag. **Why Magnesium Ammonium Phosphate is Correct:** These stones are primarily composed of **Magnesium Ammonium Phosphate (Struvite)** and calcium carbonate. They are "infection stones" caused by **urease-producing bacteria** (most commonly *Proteus mirabilis*, followed by *Klebsiella* and *Pseudomonas*). These bacteria split urea into ammonia, which increases the urinary pH (alkaline urine, pH > 7.2). In this alkaline environment, magnesium ammonium phosphate precipitates to form large, rapidly growing stones. **Analysis of Incorrect Options:** * **B. Calcium Oxalate:** This is the most common type of kidney stone overall. They are usually small, hard, and radio-opaque, but they do not typically form staghorn configurations. * **C. Uric Acid:** These stones are radiolucent (not visible on X-ray) and form in acidic urine. While they can occasionally form large stones, they are not the primary component of classic staghorn calculi. * **D. Cysteine:** These are caused by an autosomal recessive defect in amino acid transport. While they can form "partial staghorns" in children, they are much rarer than struvite stones. **High-Yield NEET-PG Pearls:** * **Microscopy:** Struvite stones show characteristic **"Coffin-lid"** crystals. * **Radiology:** They are radio-opaque (though less dense than calcium oxalate). * **Treatment:** The gold standard for staghorn calculi is **Percutaneous Nephrolithotomy (PCNL)**. * **Key Association:** Always look for a history of recurrent UTIs with alkaline urine in the clinical vignette.

Question 1

A specimen shows a nephrectomy. What is your diagnosis?

Accepted Answer

Renal cell carcinoma

Answer

Renal papillary adenoma

Answer

Urothelial cancer of renal pelvis

Answer

Oncocytoma

Question 2

Which is the most characteristic glomerular nephritis (GN) in HIV patients?

Accepted Answer

Focal Segmental Glomerulosclerosis (FSGS)

Answer

Membranoproliferative Glomerulonephritis (MPGN)

Answer

Minimal Change Disease (MCD)

Answer

Rapidly Progressive Glomerulonephritis (RPGN)

Question 3

What is the most common renal tumour?

Accepted Answer

Renal cell carcinoma

Answer

Wilm's tumour

Answer

Squamous cell carcinoma of the renal pelvis

Answer

Transitional cell carcinoma of the renal pelvis

Question 4

Bilateral renal cell carcinoma is seen in which of the following conditions?

Accepted Answer

Von Hippel-Lindau disease

Answer

Eagle-Barrett syndrome

Answer

Beckwith-Wiedemann syndrome

Answer

Bilateral angiomyolipoma

Question 5

All of the following are causes of acute tubular necrosis (ATN) except?

Accepted Answer

Placenta previa

Answer

Radiocontrasts

Answer

Amphotericin B

Answer

Abruptio placentae

Question 6

Flea bitten kidney is seen in all of the following conditions except?

Accepted Answer

Diabetes Mellitus

Answer

Malignant hypertension

Answer

Henoch-Schonlein purpura

Answer

Polyarteritis nodosa

Question 7

All of the following are causes of granular contracted kidney except?

Accepted Answer

Diabetes mellitus

Answer

Benign nephrosclerosis

Answer

Chronic pyelonephritis

Answer

Chronic glomerulonephritis

Question 8

All of the following are true about thin basement membrane defect, except:

Accepted Answer

Impaired renal function

Answer

Also known as benign familial hematuria

Answer

Autosomal dominant inheritance

Answer

Persistent or recurrent microscopic hematuria

Question 9

Which chromosomes are involved in adult polycystic kidney disease (APKD)?

Accepted Answer

4 and 16

Answer

4 and 11

Answer

4 and 12

Answer

4 and 17

Question 10

Staghorn calculus is primarily composed of which substance?

Accepted Answer

Magnesium ammonium phosphate

Answer

Calcium oxalate

Answer

Uric acid

Answer

Cysteine

Renal Pathology — MCQs

Renal Pathology — MCQs

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