Renal Pathology Practice Questions

Q: What is the pathognomonic feature of Alport syndrome?

Lenticonus and hematuria. **Explanation:** Alport Syndrome is a hereditary nephritis caused by mutations in the genes encoding the **α-chains of Type IV collagen** (most commonly *COL4A5*), which is a crucial structural component of basement membranes in the kidney, eye, and cochlea [1]. **Why Option A is Correct:** While hematuria is the most common presenting symptom [1], **Anterior Lenticonus** (a cone-shaped protrusion of the lens surface into the anterior chamber) is considered the **pathognomonic** clinical feature. It occurs in approximately 15–25% of patients and is virtually diagnostic of Alport syndrome. The combination of persistent microscopic/gross hematuria and lenticonus strongly confirms the diagnosis. **Analysis of Incorrect Options:** * **Option B & C:** While **Sensorineural Hearing Loss (SNHL)** is a classic part of the Alport triad (alongside renal failure and ocular defects), it is not pathognomonic [1]. SNHL can be found in many other genetic syndromes and environmental conditions. * **Option D:** Hyperextensibility of joints is characteristic of connective tissue disorders like Ehlers-Danlos Syndrome, not Alport syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Most common is **X-linked Dominant** (85%) [1]. * **Electron Microscopy (EM):** The classic finding is the **"Basket-weave appearance"** due to irregular thinning and thickening of the Glomerular Basement Membrane (GBM) with splitting of the lamina densa. * **The Triad:** 1. Progressive Hematuria/Renal failure, 2. Sensorineural deafness, 3. Ocular abnormalities (Lenticonus, maculopathy). * **Differential:** Thin Basement Membrane Lesion (Benign Familial Hematuria) shows only diffuse thinning of the GBM without the "basket-weave" pattern or extra-renal features [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 929-930.

Q: Which is the most likely source of Red Blood Cell (RBC) casts in a urinalysis?

Kidney. **Explanation:** The presence of **Red Blood Cell (RBC) casts** in urine is a pathognomonic finding for **glomerular bleeding** [1] or inflammation within the nephron. **Why the Kidney is the correct source:** Casts are cylindrical structures formed exclusively in the **distal convoluted tubules and collecting ducts** of the kidney. They are composed of a matrix of **Tamm-Horsfall mucoprotein** (secreted by the thick ascending limb). When RBCs leak through a damaged glomerular basement membrane (as seen in Glomerulonephritis), they become trapped within this protein matrix as it solidifies [1]. Because this molding process only occurs within the renal tubules, the presence of RBC casts localizes the source of hematuria to the renal parenchyma (specifically the glomeruli). **Why other options are incorrect:** * **Ureter, Bladder, and Urethra:** These represent the lower urinary tract. While bleeding from these sites (due to stones, trauma, or malignancy) causes hematuria, it will **not** contain casts. This is because the protein matrix required to "mold" the cells into a cast is absent in the lower tract, and the flow dynamics do not allow for cast formation. Hematuria from these sites typically shows "morphic" (normal-shaped) RBCs. **High-Yield Clinical Pearls for NEET-PG:** * **Dysmorphic RBCs (Acanthocytes):** Like RBC casts, these strongly suggest a glomerular origin (e.g., Post-streptococcal Glomerulonephritis). * **WBC Casts:** Suggest Pyelonephritis or Tubulointerstitial nephritis. * **Fatty Casts ("Maltese cross"):** Characteristic of Nephrotic Syndrome. * **Broad, Waxy Casts:** Seen in Chronic Renal Failure (due to dilated, sluggish tubules). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 520-521.

Q: All are true about post-streptococcal glomerulonephritis except?

Deposition of IgA. **Explanation:** Post-Streptococcal Glomerulonephritis (PSGN) is a classic example of a **Type III hypersensitivity reaction** (immune-complex mediated) occurring 1–4 weeks after a group A streptococcal infection (pharyngitis or impetigo) [1]. **Why Option D is the Correct Answer:** PSGN is characterized by the deposition of **IgG and Complement (C3)** along the glomerular basement membrane [1]. **IgA deposition** is the hallmark of **IgA Nephropathy (Berger’s disease)** or Henoch-Schönlein Purpura, not PSGN. Therefore, Option D is the false statement. **Analysis of Other Options:** * **Option A (Crescent formation):** While PSGN typically presents as a diffuse proliferative glomerulonephritis, severe cases can progress to **Rapidly Progressive Glomerulonephritis (RPGN)**, which is histologically characterized by crescents [1]. * **Option B (Subepithelial deposits):** Electron microscopy (EM) characteristically shows large, "hump-shaped" **subepithelial deposits**, which are immune complexes trapped between the podocytes and the basement membrane [1]. * **Option C (Granular deposits of IgG):** Immunofluorescence (IF) reveals a **"starry sky"** or "lumpy-bumpy" appearance due to the coarse granular deposition of IgG and C3 [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Serology:** Low C3 levels (hypocomplementemia) are diagnostic; levels usually return to normal within 6–8 weeks. ASOT titers are elevated after pharyngitis, while Anti-DNase B is more sensitive after skin infections (impetigo). * **Light Microscopy:** Shows "hypercellular" glomeruli due to infiltration of neutrophils and monocytes (Exudative GN) [1]. * **Prognosis:** Excellent in children (>95% recover completely); more likely to lead to chronic renal failure in adults [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 910-917.

Question 1

What is the pathognomonic feature of Alport syndrome?

Accepted Answer

Lenticonus and hematuria

Answer

Hematuria and sensorineural hearing loss

Answer

Sensorineural hearing loss and lenticonus

Answer

Hematuria and hyperextensibility of joints

Question 2

Which is the most likely source of Red Blood Cell (RBC) casts in a urinalysis?

Accepted Answer

Kidney

Answer

Ureter

Answer

Bladder

Answer

Urethra

Question 3

All are true about post-streptococcal glomerulonephritis except?

Accepted Answer

Deposition of IgA

Answer

Crescent formation

Answer

Subepithelial deposits

Answer

Granular deposits of IgG

Question 4

A large kidney is seen in all of the following conditions, except?

Accepted Answer

Benign nephrosclerosis

Answer

Amyloidosis

Answer

Diabetes mellitus

Answer

Lymphoma

Question 5

Papillary necrosis is seen in all of the following conditions except:

Accepted Answer

Shock

Answer

NSAID use

Answer

Diabetes Mellitus

Answer

Sickle cell anemia

Question 6

A 2-year-old child with leukemia develops nephrotic syndrome. Light microscopic studies are normal. Electron microscopic studies demonstrate fusion of epithelial foot processes. What is the current hypothesis for the pathogenesis of this change?

Accepted Answer

Immune complex deposition

Answer

Consumption of complement factors

Answer

IgG directed against basement membrane

Answer

Lymphokine production by T cells

Question 7

Contracted kidneys are seen in all of the following conditions except?

Accepted Answer

Amyloidosis

Answer

Chronic glomerulonephritis

Answer

Chronic renal failure

Answer

Analgesic nephropathy

Question 8

All of the following are true of Benign nephrosclerosis except?

Accepted Answer

Hyperplastic arteriolitis

Answer

Kidneys are small with fine granularity

Answer

Histological examination revealed hyaline arteriolosclerosis

Answer

Fibroelastic hyperplasia is seen

Question 9

All of the following about Xanthogranulomatous pyelonephritis is true EXCEPT?

Accepted Answer

It is associated with tuberculosis

Answer

On cut section yellowish nodules are seen

Answer

Foam cells are seen

Answer

Giant cells are seen

Question 10

Which of the following is NOT true about membranous glomerulonephritis?

Accepted Answer

Deposition between the endothelium and the basement membrane

Answer

Thickening of the basement membrane

Answer

Most common cause of nephrotic syndrome in adults

Answer

Seen in systemic lupus erythematosus, tumors, and with certain drugs

Renal Pathology — MCQs

Renal Pathology — MCQs

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