Renal Pathology Practice Questions

Q: The final stage of congenital nephrotic syndrome occurs due to gene mutations affecting which of the following proteins?

Nephrin. **Explanation:** The correct answer is **Nephrin (Option C)**. Congenital Nephrotic Syndrome of the Finnish type (CNF) is an autosomal recessive disorder caused by a mutation in the **NPHS1 gene**, which encodes the protein **Nephrin**. **Why Nephrin is correct:** Nephrin is a transmembrane protein located in the **slit diaphragm** between the foot processes of podocytes. It acts as a primary molecular sieve, preventing the leakage of albumin into the urine. In CNF, the absence or dysfunction of Nephrin leads to the complete breakdown of the filtration barrier, resulting in massive proteinuria starting in utero or shortly after birth. **Analysis of Incorrect Options:** * **Option A: Podocin:** Mutations in the **NPHS2 gene** encode Podocin. While this causes Steroid-Resistant Nephrotic Syndrome (SRNS), it typically presents in early childhood (Autosomal Recessive) rather than the classic congenital Finnish type. * **Option B: Alpha-actinin-4:** Mutations in the **ACTN4 gene** lead to an Autosomal Dominant form of Focal Segmental Glomerulosclerosis (FSGS), usually presenting in adolescence or adulthood. * **Option C: CD2-associated protein (CD2AP):** This protein anchors Nephrin to the actin cytoskeleton. Mutations are rare but are associated with sporadic cases of FSGS rather than classic congenital nephrotic syndrome. **NEET-PG High-Yield Pearls:** * **Finnish Type (NPHS1):** Presents with a large placenta (>25% of birth weight) and elevated maternal serum alpha-fetoprotein (MSAFP). * **Treatment:** CNF is resistant to steroids; definitive management requires bilateral nephrectomy followed by dialysis and renal transplantation. * **Denys-Drash Syndrome:** Characterized by early-onset nephrotic syndrome, Wilms tumor, and male pseudohermaphroditism (WT1 gene mutation).

Q: RBC casts are typically found in which of the following conditions?

Wegener's Granulomatosis. The presence of **RBC casts** in urine is a pathognomonic marker of **Glomerulonephritis (GN)** or upper urinary tract bleeding. They form when red blood cells enter the renal tubule through a damaged basement membrane and are trapped within a matrix of Tamm-Horsfall protein [1]. **Why Wegener’s Granulomatosis is correct:** Wegener’s Granulomatosis (now known as Granulomatosis with Polyangiitis or GPA) is a small-vessel vasculitis [2]. It characteristically involves the kidneys, causing **Pauci-immune Crescentic Glomerulonephritis** [3]. This condition leads to severe glomerular capillary damage, allowing RBCs to leak into the tubules and form casts [1]. It is typically associated with **c-ANCA (PR3)** positivity. **Analysis of Incorrect Options:** * **A. Diabetes Mellitus:** Typically presents with proteinuria (micro/macroalbuminuria). While it causes glomerular damage, it usually presents with **waxy casts** or fatty casts (in nephrotic stages), not RBC casts, unless there is a superimposed inflammatory GN [1]. * **C. Systemic Exertional Exertion:** While extreme exercise can cause transient hematuria or hyaline casts, it does not typically produce RBC casts, which signify structural glomerular pathology [4]. * **D. Ankylosing Spondylitis:** This is a seronegative spondyloarthropathy. While it can rarely be associated with IgA Nephropathy or secondary Amyloidosis, it is not a primary or common cause of RBC casts. **NEET-PG High-Yield Pearls:** * **RBC Casts = Nephritic Syndrome** (e.g., PSGN, RPGN, Goodpasture’s, Lupus Nephritis) [1]. * **WBC Casts** = Acute Pyelonephritis or Tubulointerstitial Nephritis. * **Muddy Brown (Granular) Casts** = Acute Tubular Necrosis (ATN). * **Fatty Casts ("Maltese Cross")** = Nephrotic Syndrome. * **Broad/Waxy Casts** = Chronic Renal Failure (due to dilated tubules).

Q: Potter's Facies is seen with which of the following conditions?

Bilateral renal agenesis. **Explanation:** **Potter’s Facies** is a characteristic physical appearance of a newborn resulting from **oligohydramnios** (low amniotic fluid). The correct answer is **Bilateral renal agenesis**, as fetal urine is the primary contributor to amniotic fluid volume in the second and third trimesters. **The Underlying Concept: Potter Sequence** When kidneys fail to develop (bilateral renal agenesis) or are obstructed, the lack of fetal urine leads to severe oligohydramnios. This results in: 1. **Mechanical Compression:** The uterine walls press directly against the fetus, causing the "Potter’s Facies" (flattened nose, recessed chin, prominent epicanthal folds, and low-set, "pressed" ears). 2. **Pulmonary Hypoplasia:** Amniotic fluid is essential for lung development; its absence is the most common cause of death in these neonates. 3. **Limb Deformities:** Clubbed feet and joint contractures due to lack of space for movement. **Analysis of Incorrect Options:** * **Xanthogranulomatous pyelonephritis:** A chronic inflammatory process (often due to *Proteus* infection) resulting in a non-functioning kidney, but it is usually unilateral and occurs later in life. * **Hepatic fibrosis:** While associated with Autosomal Recessive Polycystic Kidney Disease (ARPKD)—which *can* cause Potter sequence—isolated hepatic fibrosis does not cause oligohydramnios. * **Kasabach-Merritt Syndrome:** A rare condition involving giant hemangiomas and consumptive coagulopathy (thrombocytopenia); it has no association with renal development. **High-Yield Pearls for NEET-PG:** * **Potter Type I:** ARPKD (Infantile type). * **Potter Type II:** Renal Agenesis (Multicystic dysplastic kidney). * **Potter Type III:** ADPKD (Adult type presenting in infancy). * **Potter Type IV:** Obstructive uropathy (e.g., Posterior Urethral Valves). * **Most common cause of death:** Pulmonary hypoplasia, not renal failure.

Question 1

Which of the following is the least likely cause of necrotizing papillitis of the kidney?

Accepted Answer

Tuberculous pyelonephritis

Answer

Sickle cell disease

Answer

Diabetes mellitus

Answer

Analgesic nephropathy

Question 2

The final stage of congenital nephrotic syndrome occurs due to gene mutations affecting which of the following proteins?

Accepted Answer

Nephrin

Answer

Podocin

Answer

Alpha-actinin

Answer

CD2 activated protein

Question 3

Which of the following findings is pathognomonic of renal disease?

Accepted Answer

Coarse granular casts

Answer

Hyaline casts

Answer

Cystine crystals

Answer

Epithelial cells

Question 4

Hypocomplementemia is seen in which of the following conditions?

Accepted Answer

Post-streptococcal glomerulonephritis (PSGN)

Answer

Membranous glomerulonephritis (MGN)

Answer

Focal segmental glomerulosclerosis (FSGS) with dense deposit disease

Answer

All of the above

Question 5

HIV infection is known to cause which of the following renal pathologies?

Accepted Answer

Collapsing glomerulonephritis

Answer

Membranous glomerulonephritis

Answer

Fibrillary glomerulopathy

Answer

Rapidly progressive glomerulonephritis (RPGN)

Question 6

Which of the following can cause Rapidly Progressive Glomerulonephritis (RPGN), except?

Accepted Answer

Minimal change glomerulonephritis

Answer

Poststreptococcal glomerulonephritis

Answer

Wegener granulomatosis

Answer

Systemic Lupus Erythematosus (SLE)

Question 7

Renal papillary necrosis is seen in which of the following conditions?

Accepted Answer

Sickle cell disease

Answer

Gouty nephropathy

Answer

Chronic glomerulonephritis

Answer

Tumor necrosis syndrome

Question 8

RBC casts are typically found in which of the following conditions?

Accepted Answer

Wegener's Granulomatosis

Answer

Diabetes Mellitus

Answer

Systemic Exertional Exertion

Answer

Ankylosing Spondylitis

Question 9

Effacement of foot processes is pathognomic of which disease?

Accepted Answer

Minimal change disease

Answer

Steroid resistant glomerulonephritis

Answer

Membranous glomerulonephritis

Answer

IgA nephropathy

Question 10

Potter's Facies is seen with which of the following conditions?

Accepted Answer

Bilateral renal agenesis

Answer

Xanthogranulomatous pyelonephritis

Answer

Hepatic fibrosis

Answer

Kasabach-Merritt Syndrome

Renal Pathology — MCQs

Renal Pathology — MCQs

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