Renal Pathology Practice Questions

Q: What is the inheritance pattern of Alport syndrome?

X-linked dominant. **Explanation:** **1. Why X-linked Dominant is Correct:** Alport syndrome is a genetic disorder caused by mutations in the genes encoding **Type IV collagen**, a critical component of the glomerular basement membrane (GBM), cochlea, and lens [1]. Approximately **80% of cases** are inherited in an **X-linked dominant** fashion due to mutations in the **COL4A5** gene [1]. Because it is dominant, both hemizygous males and heterozygous females can manifest the disease, though males typically present with more severe renal failure due to the lack of a second X chromosome. **2. Why Other Options are Incorrect:** * **Autosomal Recessive (AR):** This accounts for about 15% of cases (mutations in *COL4A3* or *COL4A4*). While it exists, it is not the most common inheritance pattern. * **Autosomal Dominant (AD):** This is the rarest form (approx. 5%) and usually presents with a slower progression to end-stage renal disease (ESRD). * **X-linked Recessive:** This is incorrect because females with a single mutated *COL4A5* gene frequently show clinical symptoms (like hematuria), which defines the pattern as dominant rather than recessive. **3. NEET-PG High-Yield Clinical Pearls:** * **Classic Triad:** Hereditary nephritis (hematuria/ESRD), Sensorineural deafness, and Ocular defects (e.g., **Anterior Lenticonus**—pathognomonic). * **Electron Microscopy (EM):** Shows characteristic **"Basket-weave appearance"** due to irregular thinning and thickening of the GBM with splitting of the lamina densa [1]. * **Molecular Defect:** Defective assembly of Type IV collagen ̡3, ̡4, and ̡5 chains [1]. * **Diagnosis:** Often suspected in a child with persistent hematuria and a family history of early-onset renal failure and hearing loss [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 929-930.

Q: Presence of which of the following in the urine is diagnostic of glomerular injury?

20% dysmorphic RBCs. **Explanation:** The presence of **dysmorphic RBCs** (acanthocytes) in the urine is a hallmark of **glomerular bleeding**. When red blood cells pass through the damaged glomerular basement membrane (GBM) and travel through the varying osmotic gradients of the renal tubules, they undergo mechanical and chemical stress. This results in distorted shapes, blebs, and uneven membranes. * **Why Option B is correct:** While various thresholds exist, the presence of **>20% dysmorphic RBCs** (or specifically >5% acanthocytes/G1 cells) is highly specific and diagnostic for a glomerular source of hematuria (e.g., Glomerulonephritis [1]). * **Why Option A is incorrect:** Bright red cells (monomorphic RBCs) typically indicate **non-glomerular bleeding** from the lower urinary tract (ureters, bladder, or urethra), such as stones, trauma, or malignancy. * **Why Option C is incorrect:** The quantity of RBCs (100 RBCs/HPF) indicates significant hematuria but does not localize the site of injury. Both glomerular and post-glomerular conditions can cause high RBC counts. * **Why Option D is incorrect:** Beta-2 microglobulin is a marker used to assess **tubular function**. Elevated levels in urine indicate tubular injury or dysfunction, not necessarily glomerular basement membrane damage. **High-Yield Clinical Pearls for NEET-PG:** 1. **RBC Casts:** These are the most specific indicators of glomerular hematuria [1]. 2. **Acanthocytes:** Specifically, "mickey mouse" shaped RBCs are the most predictive type of dysmorphic cell for glomerulonephritis. 3. **Proteinuria:** Glomerular injury is often associated with significant proteinuria (>3.5g/day in nephrotic range), whereas isolated hematuria without protein often points to a lower tract cause [1]. **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. 520-532.

Q: Wire loop lesions are often characteristic for which class of lupus nephritis?

Diffuse proliferative glomerulonephritis (WHO class IV). **Explanation:** **Diffuse Proliferative Glomerulonephritis (Class IV)** is the most common and severe form of lupus nephritis [1]. The hallmark **"wire loop lesion"** occurs due to massive **subendothelial immune complex deposits** (DNA-anti-DNA complexes) [1]. These deposits cause circumferential thickening of the glomerular capillary wall, making it appear rigid and thickened like a wire under light microscopy [1]. This class involves >50% of glomeruli and is associated with the worst prognosis if untreated [1]. **Analysis of Incorrect Options:** * **Class II (Mesangial Proliferative):** Characterized by mild clinical symptoms and immune complexes restricted to the **mesangium** only. Capillary loops remain thin. * **Class III (Focal Proliferative):** Similar to Class IV but involves **<50% of glomeruli** [1]. While wire loops can occasionally be seen, they are the defining characteristic of the more extensive Class IV. * **Class IV (Membranous):** Characterized by **subepithelial deposits** (not subendothelial). It presents with nephrotic syndrome and shows uniform "spikes and domes" on silver stain, rather than wire loops. **High-Yield Clinical Pearls for NEET-PG:** * **Most common and most severe form:** Class IV (DPGN) [1]. * **Most common cause of death in SLE:** Renal failure (specifically Class IV). * **Immunofluorescence:** Shows a **"Full House" pattern** (IgG, IgA, IgM, C3, and C1q positivity). * **Electron Microscopy (EM):** Subendothelial deposits are the key to wire loops; "Fingerprint" patterns may also be seen. * **Lab Correlation:** Class IV is associated with high anti-dsDNA titers and low serum complement (C3, C4) levels. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 232.

Question 1

Glomerular basement membrane showing "tram-track" appearance is seen in which of the following conditions?

Accepted Answer

Membranoproliferative Glomerulonephritis type 1

Answer

Membranous nephropathy

Answer

Focal Segmental Glomerulosclerosis

Answer

Minimal-Change Disease

Question 2

A 55-year-old obese woman complains of declining visual acuity. Funduscopic examination shows peripheral retinal microaneurysms. Urinalysis reveals 3+ proteinuria and 3+ glucosuria. Serum albumin is 3 g/dL, and serum cholesterol is 350 mg/dL. Which of the following mechanisms best explains these clinicopathologic findings?

Accepted Answer

Peripheral insulin resistance

Answer

Increased peripheral insulin uptake

Answer

Irregular insulin secretion

Answer

None of the above

Question 3

What is the inheritance pattern of Alport syndrome?

Accepted Answer

X-linked dominant

Answer

Autosomal dominant

Answer

Autosomal recessive

Answer

X-linked recessive

Question 4

Presence of which of the following in the urine is diagnostic of glomerular injury?

Accepted Answer

20% dysmorphic RBCs

Answer

Bright red cells

Answer

100 RBCs per high power field

Answer

Beta 2 microglobulin

Question 5

Goodpasture's disease is characterized by all of the following except:

Accepted Answer

Leukocytoclastic vasculitis

Answer

Glomerulonephritis

Answer

Presence of antibodies to basement membrane

Answer

Diffuse alveolar hemorrhage

Question 6

Which of the following conditions is characterized by occasional breaks in the glomerular basement membrane and subepithelial deposits visible on electron microscopy?

Accepted Answer

Membranous glomerulonephritis (MGN)

Answer

Focal glomerular sclerosis

Answer

Rapidly progressive glomerulonephritis (RPGN)

Answer

Minimal change disease (MCD)

Question 7

What is true about acute post-infective glomerulonephritis?

Accepted Answer

Deposition of IgA

Answer

Crescent formation

Answer

Subepithelial deposits

Answer

Granular deposits of IgG

Question 8

At autopsy, a patient who had died with acute anuria and uremia is found to have ischemic necrosis of the cortex of both kidneys with relative sparing of the medulla. These pathological findings are MOST likely related to which of the following underlying conditions?

Accepted Answer

Disseminated intravascular coagulation

Answer

Multiple myeloma

Answer

Polycystic kidney disease

Answer

Pyelonephritis

Question 9

Pigmented "muddy brown" granular casts are characteristic of which of the following conditions?

Accepted Answer

Ischemic or nephrotoxic acute tubular necrosis

Answer

Prerenal acute renal failure

Answer

Postrenal acute renal failure

Answer

Chronic renal failure

Question 10

Wire loop lesions are often characteristic for which class of lupus nephritis?

Accepted Answer

Diffuse proliferative glomerulonephritis (WHO class IV)

Answer

Mesangial proliferative glomerulonephritis (WHO class II)

Answer

Focal proliferative glomerulonephritis (WHO class III)

Answer

Membranous glomerulonephritis (WHO class V)

Renal Pathology — MCQs

Renal Pathology — MCQs

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