Renal Pathology Practice Questions

Q: Which is usually a presentation of the condition shown in the immunofluorescence study of the kidney?

Development of renal vein thrombosis. ***Development of renal vein thrombosis*** - **Membranous nephropathy** causes severe **nephrotic syndrome** with massive proteinuria, leading to loss of **antithrombin III** and increased hypercoagulability. - **Renal vein thrombosis** is a classic and serious complication, occurring in up to 25% of patients with membranous nephropathy due to the hypercoagulable state. *Steroid responsive selective proteinuria* - This describes **minimal change disease**, which shows **effacement of podocyte foot processes** on electron microscopy, not granular IgG deposits. - Minimal change disease has **negative immunofluorescence**, unlike the granular pattern seen in membranous nephropathy. *Nephelometer assay showing increased serum free light chain* - This finding suggests **plasma cell dyscrasia** or **multiple myeloma**, which can cause **light chain deposition disease**. - Light chain nephropathy shows **linear or nodular deposits** of light chains, not the **granular IgG pattern** characteristic of membranous nephropathy. *Fibrillary immunotactoid glomerulopathy* - This rare condition shows **organized fibrillar deposits** on electron microscopy with **polyclonal IgG staining**. - Unlike membranous nephropathy, it typically presents with **nephritic features** including hematuria and hypertension, rather than pure nephrotic syndrome.

Q: Heroin abuse is associated with which type of glomerulonephritis?

Focal segmental glomerulosclerosis. **Explanation:** **Heroin-Associated Nephropathy (HAN)** is a classic clinical entity characterized by the development of **Focal Segmental Glomerulosclerosis (FSGS)** [1]. 1. **Why FSGS is correct:** Intravenous heroin use leads to a specific form of secondary FSGS [1]. The pathophysiology involves direct toxicity to podocytes [2], chronic inflammation, and potential contaminants in the drug. Patients typically present with massive proteinuria (nephrotic syndrome) [2] and a rapid progression to End-Stage Renal Disease (ESRD). On biopsy, it shows segmental scarring of some (but not all) glomeruli, similar to the collapsing variant seen in HIV-associated nephropathy (HIVAN) [1]. 2. **Why other options are incorrect:** * **Crescentic GN:** This is the hallmark of Rapidly Progressive Glomerulonephritis (RPGN) [3], associated with conditions like Goodpasture syndrome [4] or ANCA-associated vasculitis, not typically heroin. * **Membranous GN:** This is most commonly associated with Hepatitis B, Hepatitis C, gold therapy, or malignancies. While heroin users may have Hep B/C, the direct association of heroin itself is with FSGS [3]. * **Diffuse Proliferative GN:** This is the classic pattern for SLE (Class IV) or post-streptococcal GN [1]. **High-Yield Clinical Pearls for NEET-PG:** * **The "Collapsing" Variant:** Both Heroin and HIV are strongly associated with the collapsing variant of FSGS, which has the worst prognosis. * **Race Factor:** HAN is significantly more common in the African American population. * **Differential Diagnosis:** If a question mentions an IV drug user with **fever and hematuria**, think of **Staph. aureus Endocarditis** leading to Post-Infectious GN. If it mentions **painless nephrotic syndrome**, think of **FSGS**. * **Other FSGS associations:** Obesity, Sickle Cell Disease, and Pamidronate use.

Q: Wilms tumor is associated with all of the following except?

Bilateral polycystic kidney. **Explanation:** Wilms tumor (Nephroblastoma) is the most common primary renal tumor of childhood. It is frequently associated with specific congenital malformations and genetic syndromes [1], but **Bilateral Polycystic Kidney Disease (ADPKD/ARPKD)** is a distinct genetic ciliopathy and is **not** a recognized component of Wilms tumor associations. **Why the other options are associated with Wilms Tumor:** * **Aniridia (Option B):** This is a key feature of the **WAGR Syndrome** (Wilms tumor, Aniridia, Genitourinary anomalies, and intellectual disability/Retardation) [1]. It results from a microdeletion on chromosome 11p13 involving the *WT1* and *PAX6* genes [1]. * **Hemihypertrophy (Option A):** This is a classic feature of **Beckwith-Wiedemann Syndrome (BWS)**, characterized by organomegaly, macroglossia, and hemihypertrophy. BWS is caused by abnormalities in the 11p15.5 region (*WT2* locus). * **Hypertension (Option C):** Up to 25% of patients with Wilms tumor present with hypertension. This occurs due to increased **renin production** by the tumor cells or compression of the renal artery by the tumor mass (Goldblatt kidney mechanism). **High-Yield Clinical Pearls for NEET-PG:** * **Triphasic Morphology:** On histopathology, Wilms tumor shows three components: Blastemal (small blue cells), Stromal (fibrocytic/myxoid), and Epithelial (tubules/glomeruli). * **Denys-Drash Syndrome:** Characterized by Wilms tumor, gonadal dysgenesis, and early-onset nephropathy (diffuse mesangial sclerosis). * **Most Common Presentation:** A large, palpable, asymptomatic abdominal mass in a child (usually 2–5 years old) that does not cross the midline. * **Prognostic Factor:** The presence of **anaplasia** (p53 mutation) is the most important adverse histological prognostic factor. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 487-488.

Q: A patient presents with one normal kidney and the contralateral kidney appearing contracted with evidence of scarring. What is the most probable diagnosis?

Chronic pyelonephritis. ### Explanation **Correct Option: A. Chronic pyelonephritis** Chronic pyelonephritis (CPN) is a leading cause of **asymmetric renal disease** [1]. It is characterized by irregular, coarse, U-shaped corticomedullary scarring overlying a dilated, blunted, or deformed calyx [1]. Because the underlying causes—such as vesicoureteral reflux (VUR) or localized obstruction—often affect one kidney more severely than the other, it typically presents as a **contracted, scarred kidney** on one side with a relatively normal (or compensatorily enlarged) contralateral kidney [1]. **Why other options are incorrect:** * **B. Polycystic Kidney Disease (ADPKD):** This is a **bilateral** genetic condition. Both kidneys are typically massively enlarged with numerous cysts, rather than being small and contracted. * **C. Renal Artery Stenosis:** While this can cause a small, shrunken kidney (Goldblatt kidney) due to ischemia, the kidney surface is usually **smoothly** atrophic rather than coarsely scarred. * **D. Tuberculosis of the Kidney:** While TB can cause scarring (Putty kidney), it is usually associated with caseous necrosis and "autonephrectomy." However, the classic "contracted and scarred" description in a unilateral context is the hallmark of CPN in pathology exams. **NEET-PG High-Yield Pearls:** * **Asymmetric involvement:** The most important clue for Chronic Pyelonephritis is asymmetry [1]. * **Thyroidization of tubules:** On histology, tubules are dilated and filled with eosinophilic casts, resembling thyroid follicles [1]. * **U-shaped scars:** These are the pathognomonic gross findings of CPN, distinguishing it from the V-shaped scars of healed infarcts [1]. * **Reflux Nephropathy:** The most common cause of chronic pyelonephritis in children [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 937-940.

Q: A 60-year-old man presents with acute renal insufficiency. He treated his garden last week with a number of herbicides and insecticides, some of which may have contained heavy metals. Laboratory studies confirm oliguria and increased levels of BUN (54 mg/dL) and creatinine (3.7 mg/dL). A renal biopsy is shown. What is the most likely diagnosis?

Acute tubular necrosis (ATN). ***Acute tubular necrosis (ATN)*** - **Heavy metal exposure** from herbicides/insecticides is a classic **nephrotoxic cause** of ATN, leading to tubular epithelial cell death and oliguria. - Histologically shows **tubular cell flattening**, **loss of brush border**, and **tubular casts** with preserved glomeruli and interstitium. *Bilateral cortical necrosis* - Caused by severe **ischemic events** like **obstetric emergencies** or **severe shock**, not nephrotoxic exposure. - Histology shows **extensive cortical infarction** affecting both tubules and glomeruli, which is more severe than ATN. *Papillary necrosis* - Associated with **chronic analgesic abuse** (NSAIDs), **diabetes mellitus**, or **sickle cell disease**. - Affects the **renal medulla and papillae** specifically, not the cortical tubules primarily affected by heavy metals. *Rapidly progressive glomerulonephritis* - Characterized by **glomerular crescents** and **proteinuria/hematuria**, not primarily oliguria from tubular damage. - Caused by **anti-GBM antibodies**, **ANCA-associated vasculitis**, or **immune complex disease**, not heavy metal toxicity.

Q: Dysmorphic RBCs with acute renal failure (ARF) are most commonly seen in which condition?

Glomerular disease. The presence of **dysmorphic Red Blood Cells (RBCs)** in urine is a hallmark of **Glomerular disease** [1]. When RBCs pass through the damaged glomerular basement membrane (GBM) and travel through the varying osmotic gradients of the renal tubules, they undergo mechanical trauma and osmotic stress. This results in morphological changes such as blebbing, fragmentation, and the formation of **acanthocytes** (G1 cells), which are highly specific for glomerular bleeding. In the context of Acute Renal Failure (ARF), this finding strongly suggests **Acute Glomerulonephritis (AGN)** or Rapidly Progressive Glomerulonephritis (RPGN) [1]. **Analysis of Incorrect Options:** * **Renal Carcinoma:** This typically causes **isomorphic (normal-shaped) RBCs** because the bleeding occurs from the vascular supply of the tumor into the collecting system, bypassing the mechanical stress of the glomerular filter [1]. * **Proximal and Distal Tubule Disease:** While tubular diseases (like Acute Tubular Necrosis) are common causes of ARF, they typically present with **casts** (e.g., muddy brown casts) and tubular epithelial cells rather than dysmorphic RBCs. Hematuria is not a primary feature of isolated tubular injury. **NEET-PG High-Yield Pearls:** * **Acanthocytes:** The most specific type of dysmorphic RBC; if >5% of total urinary RBCs are acanthocytes, glomerular disease is highly likely. * **RBC Casts:** These are pathognomonic for glomerular hemorrhage. * **Isomorphic RBCs:** Suggest "urological" bleeding (stones, malignancy, or infections). * **Phase-contrast microscopy:** The gold standard method for identifying RBC morphology in urine.

Question 1

Which is usually a presentation of the condition shown in the immunofluorescence study of the kidney?

Accepted Answer

Development of renal vein thrombosis

Answer

Steroid responsive selective proteinuria

Answer

Nephelometer assay showing increased serum free light chain

Answer

Fibrillary immunotactoid glomerulopathy

Question 2

Heroin abuse is associated with which type of glomerulonephritis?

Accepted Answer

Focal segmental glomerulosclerosis

Answer

Crescentic glomerulonephritis

Answer

Membranous glomerulonephritis

Answer

Diffuse proliferative glomerulonephritis

Question 3

Renal biopsy demonstrates concentric, laminated thickening of arteriolar walls due to proliferation of smooth muscle cells. This process is best described by which of the following terms?

Accepted Answer

Hyperplastic arteriolosclerosis

Answer

Atherosclerosis

Answer

Hyaline arteriolosclerosis

Answer

Monckeberg's arteriosclerosis

Question 4

Which of the following is the characteristic histological feature of HIV-associated collapsing glomerulopathy?

Accepted Answer

Hypertrophy and proliferation of visceral epithelial cells

Answer

Crescent formation

Answer

Mesangial deposition

Answer

Subepithelial deposition with endothelial cell proliferation

Question 5

Wilms tumor is associated with all of the following except?

Accepted Answer

Bilateral polycystic kidney

Answer

Hemihypertrophy

Answer

Aniridia

Answer

Hypertension

Question 6

A patient presents with one normal kidney and the contralateral kidney appearing contracted with evidence of scarring. What is the most probable diagnosis?

Accepted Answer

Chronic pyelonephritis

Answer

Polycystic kidney disease

Answer

Renal artery stenosis

Answer

Tuberculosis of the kidney

Question 7

Most unlikely cause of acute tubular necrosis amongst the following is?

Accepted Answer

Rupture of aortic aneurysm

Answer

Severe bacterial infection

Answer

Massive burn

Answer

Severe crush injury

Question 8

A 60-year-old man presents with acute renal insufficiency. He treated his garden last week with a number of herbicides and insecticides, some of which may have contained heavy metals. Laboratory studies confirm oliguria and increased levels of BUN (54 mg/dL) and creatinine (3.7 mg/dL). A renal biopsy is shown. What is the most likely diagnosis?

Accepted Answer

Acute tubular necrosis (ATN)

Answer

Bilateral cortical necrosis

Answer

Papillary necrosis

Answer

Rapidly progressive glomerulonephritis

Question 9

Dysmorphic RBCs with acute renal failure (ARF) are most commonly seen in which condition?

Accepted Answer

Glomerular disease

Answer

Renal carcinoma

Answer

Proximal tubule disease

Answer

Distal tubule disease

Question 10

Edema in nephrotic syndrome occurs due to:

Accepted Answer

Decreased serum albumin

Answer

Sodium and water restrictions

Answer

Increased venous pressure

Answer

Decreased fibrinogen

Renal Pathology — MCQs

Renal Pathology — MCQs

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