Renal Pathology Practice Questions

Q: Which of the following is a feature of autosomal recessive polycystic kidney disease?

Can be diagnosed intrauterine. **Explanation:** **Autosomal Recessive Polycystic Kidney Disease (ARPKD)** is a genetic disorder caused by mutations in the **PKHD1 gene** on chromosome 6, which encodes **fibrocystin** [1]. 1. **Why Option A is correct:** ARPKD can be diagnosed **intrauterine** via prenatal ultrasound. Characteristic findings include bilaterally enlarged, echogenic kidneys and **oligohydramnios** (due to poor fetal urine output). Severe cases present at birth (Potter sequence) with pulmonary hypoplasia [1]. 2. **Why other options are incorrect:** * **Option B:** While some patients survive to school age, the classic "infantile" form often leads to **perinatal or neonatal death** due to respiratory failure [1]. It does not "progress" to failure by school age; rather, those who survive birth usually already have significant renal impairment. * **Option C:** While the kidneys are massively enlarged, they are typically described as **smooth and symmetrical** (due to small, radially arranged cortical cysts), unlike the "bosselated" or "knobby" irregular masses palpated in Autosomal Dominant PKD (ADPKD). * **Option D:** Hypertension is a **very early and severe** feature of ARPKD, often appearing in the neonatal period, and is a major cause of morbidity. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** Characterized by **cylindrical/saccular dilation of collecting ducts** (radial arrangement) [1]. * **Liver Involvement:** 100% of cases have **Congenital Hepatic Fibrosis**. If the patient survives the renal complications, they often present later with portal hypertension and splenomegaly. * **Potter Sequence:** Oligohydramnios → Fetal compression → Clubbed feet, flattened facies, and pulmonary hypoplasia. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 952-953.

Q: A patient with renal disease undergoes a biopsy. On Congo red staining, the deposits show apple-green birefringence under polarised light. What is the most likely diagnosis?

Amyloidosis. ***Amyloidosis***- This feature is the **pathognomonic microscopic manifestation** of amyloid deposition, where the Congo red stain binds specifically to the parallel **cross-beta sheet** configuration of amyloid fibrils [1].- When viewed under **polarized light**, this interaction results in the classic **apple-green birefringence** due to the ordering of the deposited protein [1], [2]. *Minimal change disease*- The diagnosis of minimal change disease relies primarily on **electron microscopy**, which shows **effacement of podocyte foot processes**.- On **light microscopy**, the glomeruli appear virtually normal, and there are no deposits present that would stain positively with Congo red. *Diabetic nephropathy*- Characteristic findings on light microscopy include **diffuse mesangial expansion** and the formation of **Kimmelstiel-Wilson nodules** (nodular glomerulosclerosis).- The thickening of the glomerular basement membrane and mesangial expansion are due to hyperglycemia and associated metabolic changes, not amyloid deposition. *Membranous nephropathy*- This nephropathy is defined by the presence of **subepithelial immune complex deposits** that result in a uniformly thickened glomerular basement membrane (GBM).- Silver stains often reveal a classic **"spike and dome"** pattern on the GBM, which is distinct from amyloid fibrils. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 268-269. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 533-534.

Q: Tamm-Horsfall mucoprotein is a major component of which of the following?

Renal casts. ***Renal casts*** - **Tamm-Horsfall mucoprotein (THP)**, or **uromodulin**, is a glycoprotein synthesized by the tubular epithelial cells of the **thick ascending limb of the loop of Henle** and the distal tubule. - It forms the fundamental matrix of virtually all **renal casts** (hyaline, granular, waxy, fatty, etc.) when it precipitates in the concentrated, acidic environment of the distal nephron [1]. *Mural thrombi* - These are formed within blood vessels or the heart chambers and consist primarily of aggregated **platelets**, **fibrin**, and entrapped red blood cells. - Mural thrombi are related to circulatory pathology (e.g., atrial fibrillation, myocardial infarction) and are distinct from urinary tract components. *Curschmann spirals* - These spiral-shaped mucoid structures are found in the sputum of patients with conditions like severe bronchial **asthma** or chronic bronchitis. - They represent casts of small bronchi or bronchioles composed mainly of **mucus**, glycoproteins, and cellular debris produced by goblet cells and mucous glands. *Bence-Jones proteins* - These are **free monoclonal light chains** (kappa or lambda) of immunoglobulins that appear in the urine due to overproduction by pathologically proliferating plasma cells, most commonly in **multiple myeloma** [1]. - Bence-Jones proteins are filtered plasma proteins and are distinct from Tamm-Horsfall protein which is secreted by the renal tubular cells [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 942-943.

Q: Least common finding in diabetic kidney is

Armanni-Ebstein. ***Armanni-Ebstein*** - **Armanni-Ebstein lesion** (also known as Armanni-Ebstein change) refers to severe **glycogen accumulation** in the tubular epithelial cells, typically the proximal tubules. - This finding is relatively rare and seen mainly in cases of **poorly controlled acute diabetes mellitus** or acute hyperglycemia, making it the least common routine finding compared to the other structural changes. ***Podocyte loss*** - **Podocyte injury (podocytopathy)** and subsequent loss are a central and early feature in the pathogenesis of diabetic nephropathy, leading to **proteinuria**. - Progressive effacement, detachment, and eventual depletion of these highly specialized cells are constant findings in established **diabetic kidney disease (DKD)**. ***Mesangial widening*** - **Mesangial expansion/widening** is considered the earliest and most specific histological change in **diabetic nephropathy**. - This pathology progresses, leading eventually to **diffuse or nodular glomerulosclerosis** (**Kimmelstiel-Wilson lesions**), making it a universal finding in established DKD. ***GBM thickening*** - **Glomerular basement membrane (GBM) thickening** occurs very early in **diabetic nephropathy**, often preceding clinical proteinuria [1]. - It is a consistent and measurable structural abnormality caused by increased synthesis and altered composition of **extracellular matrix** components in the GBM [1], [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1119-1121. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 907-908.

Q: In renal transplant biopsy, which of the following stains is not used to identify organisms?

Congo red. ***Congo red*** - **Congo red** is a special stain primarily used to look for **amyloid deposition**, which appears as an apple-green birefringence under polarized light [1]. - It is a diagnostic stain for **amyloidosis** and has **no role in the identification of infectious organisms** (bacteria, fungi, or parasites) in tissue biopsies [2]. - This is the stain that is **NOT used to identify organisms** in renal transplant biopsies. *Gomori methenamine silver* - This stain, often abbreviated as **GMS**, is excellent for demonstrating the cell walls of **fungi** (e.g., *Pneumocystis*, *Aspergillus*, *Cryptococcus*) which appear as black structures. - It is frequently used in transplant pathology to rule out opportunistic fungal infections. *PAS (Periodic acid-Schiff) stain* - **PAS** stain is used to highlight mucopolysaccharides, basement membranes, and certain cell walls, making it useful for identifying various organisms. - It stains the cell walls of **fungi** and the capsules of some organisms, making it valuable in detecting infections. *Masson Fontana* - **Masson Fontana** stain is primarily used to identify **melanin** pigment in tissues. - While it is not a standard organism identification stain in routine renal transplant pathology, specialized silver-based modifications have been described for detecting certain fungal organisms in research settings. - However, it is not considered a primary stain for organism identification in clinical practice. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 268-269. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 533-534.

Q: All the following are features of Polycystic disease of kidneys EXCEPT:

Erythrocytosis. ***Erythrocytosis*** - While other renal conditions like **renal cell carcinoma** can cause erythrocytosis due to increased **erythropoietin** production, it is generally **not a typical feature** of Polycystic Kidney Disease (PKD). - Patients with PKD usually have **normal or even low erythropoietin levels** despite compromised kidney function, and anemia is more common, particularly as **renal failure progresses**. *Renal failure* - **Progressive cyst growth** leads to replacement of normal kidney parenchyma, inevitably culminating in **end-stage renal disease** [1] in the majority of patients. - This is a hallmark feature, often necessitating **dialysis or transplant** later in life for individuals with autosomal dominant polycystic kidney disease (ADPKD) [2]. *Haematuria* - **Gross or microscopic hematuria** is a common symptom in PKD, often resulting from **cyst rupture** [1], bleeding into a cyst, or the passage of a calculus due to urinary stasis. - It can be a presenting symptom and can cause significant pain and anxiety for patients. *Hypertension* - **Hypertension** is an early and frequent complication of PKD, often preceding any significant decline in glomerular filtration rate. - It is primarily caused by activation of the **renin-angiotensin-aldosterone system (RAAS)** [3] due to arterial compression and ischemia from expanding cysts. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 951-955. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 544-545. [3] 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.

Question 1

Congenital hepatic fibrosis is a characteristic feature of which of the following conditions?

Accepted Answer

Autosomal Recessive Polycystic Kidney Disease (ARPKD)

Answer

Multicystic renal dysplasia

Answer

Familial juvenile nephronophthisis

Answer

Medullary sponge kidney

Question 2

Which of the following is a feature of autosomal recessive polycystic kidney disease?

Accepted Answer

Can be diagnosed intrauterine

Answer

Progresses to renal failure by school age

Answer

Can be palpated abdominally

Answer

Hypertension does not develop until late stages of the disease

Question 3

A patient with renal disease undergoes a biopsy. On Congo red staining, the deposits show apple-green birefringence under polarised light. What is the most likely diagnosis?

Accepted Answer

Amyloidosis

Answer

Diabetic nephropathy

Answer

Membranous nephropathy

Answer

Minimal change disease

Question 4

A 5-year-old child presented with a history of edema of the face which later progressed to generalized edema. Urine showed massive proteinuria and light microscopy was normal. Electron microscopy showed effacement of podocyte foot processes. What is the diagnosis?

Accepted Answer

Minimal change disease

Answer

Post streptococcal glomerulonephritis

Answer

Focal segmental glomerulo sclerosis

Answer

Membranous glomerulonephritis

Question 5

Tamm-Horsfall mucoprotein is a major component of which of the following?

Accepted Answer

Renal casts

Answer

Bence-Jones proteins

Answer

Mural thrombi

Answer

Curschmann spirals

Question 6

Least common finding in diabetic kidney is

Accepted Answer

Armanni-Ebstein

Answer

Podocyte loss

Answer

GBM thickening

Answer

Mesangial widening

Question 7

In renal transplant biopsy, which of the following stains is not used to identify organisms?

Accepted Answer

Congo red

Answer

Masson Fontana

Answer

PAS (Periodic acid-Schiff) stain

Answer

Gomori methenamine silver

Question 8

All the following are features of Polycystic disease of kidneys EXCEPT:

Accepted Answer

Erythrocytosis

Answer

Renal failure

Answer

Haematuria

Answer

Hypertension

Question 9

A renal biopsy shows 'bamboo spine' pattern in arterioles. Which immunofluorescence finding would best support thrombotic microangiopathy?

Accepted Answer

Minimal/negative immunofluorescence staining

Answer

Mesangial IgA deposits

Answer

Linear IgG deposits

Answer

Granular C3 deposits

Question 10

A kidney biopsy shows 'tram-track' appearance on silver stain. Which immunofluorescence pattern would best support membranoproliferative glomerulonephritis?

Accepted Answer

Granular C3 and IgG deposits

Answer

Granular C3 deposits

Answer

Mesangial IgA deposits

Answer

Fibrillar deposits

Renal Pathology — MCQs

Renal Pathology — MCQs

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