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Iraqi Board Pathology study materials
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Iraqi Board Pathology practice questions

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Question 1General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 58-year-old man with a 40-pack-year smoking history presents with a central lung mass. Histology shows pleomorphic cells with hyperchromatic nuclei, prominent nucleoli, and numerous atypical mitoses invading the bronchial wall. Which biological property of malignant neoplasms does the presence of atypical mitoses best illustrate?

  1. Ability to induce new blood vessel formation
  2. Autonomous, limitless proliferative capacity Correct answer.
  3. Escaping growth-suppressive signals of the tissue
  4. Defective intercellular cohesion allowing invasion

Explanation

Atypical mitoses indicate disordered, unchecked cell division, which reflects the autonomous proliferative capacity that defines neoplastic growth after oncogenic mutations. Loss of contact inhibition and growth-control checkpoints allows continuous replication independent of normal tissue demands.

Question 2General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

During an acute inflammatory response, which vascular change is responsible for the earliest slowing of blood flow in the affected capillary bed?

  1. Vasoconstriction of arterioles followed by sustained vasodilation Correct answer.
  2. Increased lymphatic drainage from the interstitium
  3. Deposition of fibrin within the vessel lumen
  4. Contraction of endothelial cells opening intercellular gaps

Explanation

Acute inflammation begins with transient arteriolar vasoconstriction followed by vasodilation of arterioles and capillary beds, which increases blood flow and then slows it as vessels engorge. This stasis allows leukocytes to marginate and contact the endothelium.

Question 3General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 62-year-old woman has a firm, painless breast mass. Biopsy shows nests of malignant cells surrounded by abundant dense collagenous stroma. This desmoplastic reaction is most directly responsible for which clinical feature?

  1. Firm, gritty consistency on palpation Correct answer.
  2. Rapid fluctuation in size with menses
  3. Pulsatile bruit over the mass
  4. Yellowish discoloration of the overlying skin

Explanation

Desmoplasia is the production of dense fibrous connective tissue by stromal cells in response to tumour, giving scirrhous carcinomas a hard, gritty texture. This is characteristic of invasive ductal carcinoma of the breast.

Question 4General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which cellular adaptation is best described as a decrease in the size of an organ due to reduction in cell size and number after prolonged immobilisation of a limb?

  1. Hyperplasia
  2. Hypertrophy
  3. Metaplasia
  4. Atrophy Correct answer.

Explanation

Atrophy is a reduction in cell size and, often, cell number, producing a smaller organ; disuse of a limb is a classic cause through decreased protein synthesis and increased ubiquitin-proteasome degradation. Hypertrophy and hyperplasia are increases, and metaplasia is a change of cell type.

Question 5General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 45-year-old man sustains a crush injury to the thigh. Two days later he develops acute kidney injury with dark urine and a serum creatine kinase of 40,000 U/L. Which mechanism best explains the renal injury?

  1. Renal vein thrombosis with congestion
  2. Myoglobin-induced tubular obstruction and direct tubular toxicity Correct answer.
  3. Antibody-mediated basement membrane damage
  4. Immune complex deposition in glomerular capillaries

Explanation

Rhabdomyolysis releases myoglobin, which is filtered and precipitates in tubules, causing cast obstruction and direct toxic injury, especially in acidic urine. This produces pigment nephropathy with acute tubular necrosis.

Question 6General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

In a healing myocardial infarct, which cell type replaces the necrotic tissue after approximately two weeks and is responsible for the eventual scar?

  1. Neutrophils and macrophages
  2. Regenerating cardiomyocytes
  3. Fibroblasts and newly formed capillaries Correct answer.
  4. Smooth muscle cells of the media

Explanation

Because cardiac muscle cannot regenerate, healing proceeds by organisation: granulation tissue composed of proliferating fibroblasts and new capillaries replaces the necrotic zone and matures into a collagenous scar. Neutrophils and macrophages dominate earlier, and cardiomyocytes do not replicate meaningfully.

Question 7General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 30-year-old woman has recurrent deep vein thrombosis and a history of two first-trimester pregnancy losses. Laboratory testing shows a functional assay abnormality that is not corrected by mixing with normal plasma. Which mechanism most likely underlies her hypercoagulable state?

  1. Antithrombin deficiency
  2. Antiphospholipid antibody syndrome
  3. Protein C deficiency
  4. Activated protein C resistance due to factor V Leiden Correct answer.

Explanation

Factor V Leiden causes activated protein C resistance, so the anticoagulant effect of APC on factor Va is lost. A functional APC-resistance assay remains abnormal on mixing with normal plasma because the abnormal factor Va substrate persists.

Question 8General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which morphological feature distinguishes a malignant tumour from a benign tumour on histology?

  1. Infiltration of surrounding tissue with destruction of normal architecture Correct answer.
  2. Slow growth over several years
  3. Uniform cells with low nuclear-to-cytoplasmic ratio
  4. Presence of a fibrous capsule

Explanation

Malignant neoplasms invade and destroy adjacent tissue, whereas benign tumours remain circumscribed and push rather than infiltrate. Capsulation, uniform cytology, and slow growth are features more typical of benign lesions.

Question 9General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 24-year-old man develops a swollen, erythematous arm after an insect bite. The lesion is warm and indurated. Which mediator is chiefly responsible for the increased vascular permeability in this early phase?

  1. Transforming growth factor beta from platelets
  2. Histamine released from mast cells Correct answer.
  3. Complement C3b opsonising bacteria
  4. Interleukin-1 produced by macrophages

Explanation

Histamine released from mast cells causes endothelial cell contraction and increased venular permeability within minutes, producing the immediate wheal-and-flare response. IL-1 and TGF-beta act later, and C3b is an opsonin rather than a permeability mediator.

Question 10General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 55-year-old woman with chronic hepatitis C develops cirrhosis. Which parenchymal change best accounts for the portal hypertension?

  1. Acute fatty change without inflammation
  2. Biliary epithelial metaplasia of hepatocytes
  3. Diffuse hepatocyte hypertrophy without fibrosis
  4. Deposition of fibrous septa with regenerative nodules distorting the sinusoidal architecture Correct answer.

Explanation

Cirrhosis is defined by bridging fibrosis and regenerative nodules that distort hepatic vasculature, increasing sinusoidal resistance and causing portal hypertension. Steatosis or hypertrophy alone does not produce this resistance.

Question 11General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which type of necrosis characteristically occurs in the brain after an ischaemic infarct?

  1. Fat necrosis
  2. Liquefactive necrosis Correct answer.
  3. Coagulative necrosis
  4. Caseous necrosis

Explanation

Ischaemic injury in the central nervous system produces liquefactive necrosis because enzymatic digestion predominates and the dead tissue becomes a cystic cavity. Coagulative necrosis is typical of infarcts in solid organs such as heart and kidney.

Question 12General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 67-year-old man with atrial fibrillation suddenly develops a pale, cold, pulseless leg. Which sequence best describes the resulting tissue injury?

  1. Immediate apoptotic death of all ischaemic cells with intact membranes
  2. Rapid regeneration of skeletal muscle within hours
  3. Complement-mediated lysis of endothelial cells
  4. ATP depletion, failure of the sodium-potassium pump, cell swelling, and calcium influx Correct answer.

Explanation

Ischaemia halts oxidative phosphorylation, depleting ATP; the Na+/K+ ATPase fails, sodium and water enter, and cells swell. Loss of calcium homeostasis and mitochondrial damage then drive irreversible injury.

Question 13General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 35-year-old woman has a painless thyroid nodule. Fine-needle aspiration shows uniform follicles lined by bland cells with colloid, arranged in a well-circumscribed lesion. Which feature would most reliably indicate malignancy if present?

  1. Formation of small follicles
  2. Abundant colloid within follicles
  3. Presence of a fibrous capsule
  4. Capsular invasion by follicular cells Correct answer.

Explanation

In a follicular lesion, the diagnosis of carcinoma rests on capsular or vascular invasion rather than cytology, because benign and malignant follicular cells look similar. Colloid, follicle formation, and even a capsule can be seen in adenomas.

Question 14General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 40-year-old man develops a painless swelling of the parotid gland that has grown slowly over five years. Histology shows a well-circumscribed lesion with epithelial and myxochondroid components. Which term best describes this mixed pattern?

  1. Mucoepidermoid carcinoma
  2. Pleomorphic adenoma Correct answer.
  3. Oncocytoma
  4. Warthin tumour

Explanation

Pleomorphic adenoma is a benign mixed tumour containing epithelial and mesenchymal-like (myxochondroid) elements, typically arising in the parotid. Its circumscribed, slow-growing behaviour fits the clinical description.

Question 15General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 28-year-old woman has a positive tuberculin skin test but no symptoms. Which cell type forms the granuloma seen in the lung apex on chest radiography?

  1. Epithelioid macrophages derived from circulating monocytes Correct answer.
  2. Neutrophils recruited by IL-8
  3. Cytotoxic T lymphocytes directly lysing bacilli
  4. Eosinophils responding to IgE

Explanation

Granulomas are formed by epithelioid macrophages, which are activated monocytes, often with multinucleated giant cells and a rim of lymphocytes. This is a type IV cell-mediated response to persistent intracellular organisms.

Question 16General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 50-year-old man with a long-standing duodenal ulcer presents with sudden haematemesis. Endoscopy shows a bleeding vessel in the ulcer base. Which vessel is most commonly eroded in posterior duodenal ulcers?

  1. Gastroduodenal artery Correct answer.
  2. Superior mesenteric artery
  3. Splenic artery
  4. Left gastric artery

Explanation

Posterior duodenal ulcers may erode the gastroduodenal artery, which runs behind the first part of the duodenum, causing severe haemorrhage. Anterior ulcers tend to perforate into the peritoneal cavity instead.

Question 17General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which molecular alteration is most characteristic of the transition from a benign colonic adenoma to invasive adenocarcinoma?

  1. Translocation of BCR-ABL
  2. Single germline mutation in RB1
  3. Sequential accumulation of mutations in APC, KRAS, and TP53 Correct answer.
  4. Amplification of HER2 in all adenomas

Explanation

The adenoma-carcinoma sequence involves stepwise mutations, typically starting with APC loss, followed by KRAS activation and later TP53 inactivation. This cumulative genetic model explains increasing dysplasia and eventual invasion.

Question 18General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 70-year-old woman dies of a large cerebral haemorrhage. At autopsy the brain shows a haematoma in the basal ganglia. Which underlying vascular change most commonly predisposes to this event?

  1. Temporal arteritis of the scalp vessels
  2. Cystic medial degeneration of the aorta
  3. Hyaline arteriolosclerosis of penetrating arteries Correct answer.
  4. Fibromuscular dysplasia of the carotid artery

Explanation

Chronic hypertension causes hyaline arteriolosclerosis in small penetrating arteries such as the lenticulostriate vessels, predisposing to Charcot-Bouchard microaneurysms and basal ganglia haemorrhage.

Question 19General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 22-year-old man has a wound sutured after a laceration. Which process begins first during healing by primary intention?

  1. Re-epithelialisation across the wound surface
  2. Formation of a fibrin clot with platelet degranulation Correct answer.
  3. Deposition of type III collagen by fibroblasts
  4. Contraction of the wound by myofibroblasts

Explanation

Haemostasis is the first phase: platelets aggregate and degranulate, and a fibrin clot forms the provisional matrix. Fibroblast collagen deposition, epithelial migration, and myofibroblast contraction occur in later phases.

Question 20General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 60-year-old man with nephrotic syndrome has a renal biopsy showing amorphous eosinophilic material in the mesangium that stains with Congo red and shows apple-green birefringence under polarised light. Which protein most likely constitutes this deposit?

  1. Calcium phosphate crystals
  2. Fibrinogen within glomerular capillaries
  3. Immunoglobulin G immune complexes
  4. Amyloid fibrils composed of misfolded protein Correct answer.

Explanation

Congo red positivity with apple-green birefringence is diagnostic of amyloid, which consists of misfolded fibrillar proteins deposited extracellularly. In renal involvement this produces proteinuria and nephrotic syndrome.

Question 21General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which feature of malignant cells allows them to metastasise through the bloodstream?

  1. Retention of basement membrane integrity
  2. Loss of E-cadherin-mediated adhesion and acquisition of migratory capacity Correct answer.
  3. Increased expression of tight junction proteins
  4. Enhanced apoptosis after detachment

Explanation

Epithelial-mesenchymal transition reduces E-cadherin, loosening intercellular adhesion and enabling invasion through basement membranes and entry into vessels. Metastasising cells must also resist anoikis, not enhance it.

Question 22General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 33-year-old woman has a butterfly rash, joint pains, and proteinuria. A renal biopsy shows wire-loop lesions. Which mechanism best explains these lesions?

  1. Direct cytotoxic T-cell destruction of podocytes
  2. Ischaemic necrosis from renal artery stenosis
  3. Amyloid deposition in the mesangium
  4. Subendothelial deposition of immune complexes Correct answer.

Explanation

Lupus nephritis produces subendothelial immune complex deposits, which thicken capillary walls and appear as wire loops on light microscopy. This is a type III hypersensitivity reaction.

Question 23General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which of the following best describes the mechanism by which free radicals cause cell injury?

  1. Direct inhibition of mitochondrial ribosomes
  2. Activation of caspase-independent necrosis only
  3. Peroxidation of membrane lipids and oxidative damage to DNA and proteins Correct answer.
  4. Reversible binding to the sodium-potassium pump

Explanation

Reactive oxygen species attack unsaturated fatty acids in membranes, causing lipid peroxidation, and damage DNA and proteins, leading to membrane disruption and cell death. Antioxidants such as glutathione normally neutralise them.

Question 24General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 45-year-old woman has a firm, mobile mass in the uterine wall. Histology shows interlacing bundles of smooth muscle cells with cigar-shaped nuclei and no necrosis or significant mitoses. Which diagnosis is most likely?

  1. Endometrial carcinoma
  2. Leiomyosarcoma
  3. Adenomyosis
  4. Leiomyoma Correct answer.

Explanation

Leiomyoma is a benign smooth muscle tumour with interlacing bundles, uniform spindle cells, and absent coagulative tumour necrosis or marked atypia. Leiomyosarcoma shows atypia, necrosis, and frequent mitoses.

Question 25General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 55-year-old man has a chronic non-healing leg ulcer with raised, rolled edges and a pearly appearance. Biopsy shows islands of atypical squamous cells invading the dermis with keratin pearls. Which aetiological factor most strongly predisposes to this lesion?

  1. Epstein-Barr virus infection
  2. Human papillomavirus type 6 infection
  3. Chronic ultraviolet radiation exposure Correct answer.
  4. Chronic Helicobacter pylori gastritis

Explanation

Squamous cell carcinoma of sun-exposed skin is strongly associated with cumulative ultraviolet radiation, which induces TP53 mutations. Keratin pearls and dermal invasion confirm squamous differentiation.

Question 26General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 58-year-old man with a history of stable angina develops crushing chest pain that radiates to his left arm. An electrocardiogram shows ST-segment elevation in the anterior leads. Which ultrastructural change is the earliest irreversible event in the cardiomyocytes deprived of blood supply?

  1. Severe mitochondrial vacuolisation
  2. Swelling of the endoplasmic reticulum
  3. Rupture of lysosomes with release of enzymes
  4. Loss of integrity of the plasma membrane Correct answer.

Explanation

Irreversible cell injury is defined by the inability to restore the cell to a normal state, and the critical event that marks this point is loss of plasma membrane integrity. This allows extracellular calcium to flood the cell and enzymes to leak out, which is why serum troponin becomes detectable. Mitochondrial vacuolisation, ER swelling, and lysosomal rupture are features of reversible injury or occur secondary to membrane failure.

Question 27General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 29-year-old woman has a purulent discharge from a surgical wound. The wound is drained and a course of antibiotics is started. Which sequence of cellular events best describes the resolution of this acute inflammatory exudate?

  1. Neutrophils degranulate and release collagen, which permanently replaces the exudate
  2. Fibroblasts engulf the neutrophils and transform into myofibres
  3. Exudate is converted into a granuloma by epithelioid histiocytes
  4. Neutrophils undergo apoptosis and are phagocytosed by macrophages, which then leave the site via lymphatics Correct answer.

Explanation

In uncomplicated acute inflammation, neutrophils have a short lifespan and undergo apoptosis after their function is complete. Macrophages recognise and phagocytose the apoptotic neutrophils, and the macrophages themselves later exit through lymphatics or undergo apoptosis. This process clears the exudate without scarring, provided the tissue architecture is preserved.

Question 28General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 62-year-old man has a large chronic leg ulcer that has failed to heal for six months. Histology of the ulcer edge shows a proliferation of small blood vessels lined by plump endothelial cells, mixed with oedema and a chronic inflammatory infiltrate. Which process does this histological picture represent?

  1. Caseous necrosis
  2. Coagulative necrosis
  3. Granulation tissue Correct answer.
  4. Liquefactive necrosis

Explanation

Granulation tissue is the hallmark of healing and consists of proliferating small blood vessels (angiogenesis) set in a loose oedematous stroma with macrophages, fibroblasts, and chronic inflammatory cells. It fills the defect before mature collagen scar replaces it. Its plump endothelial cells and high vascularity distinguish it from necrosis and from mature fibrous tissue.

Question 29General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 47-year-old woman has a 3 cm mass in the colon. Biopsy shows a well-circumscribed proliferation of glands lined by uniform, bland cells with no invasion through the muscularis mucosae. Which feature would most strongly indicate that this lesion has become malignant?

  1. Presence of abundant eosinophilic cytoplasm
  2. Penetration of the basement membrane and invasion of the submucosa Correct answer.
  3. A high nuclear-to-cytoplasmic ratio
  4. Formation of glandular structures

Explanation

The defining feature of malignancy is the ability to invade and metastasise, so penetration of the basement membrane and extension into underlying tissue is the most reliable evidence of transformation from adenoma to carcinoma. Cytological atypia and architectural complexity are supportive but can occur in benign lesions. Gland formation and abundant cytoplasm are seen in both benign and malignant epithelium.

Question 30General Pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 54-year-old man with a history of recurrent pulmonary embolism is found to have a thrombus in the right popliteal vein. Which combination of factors in Virchow's triad best explains venous thrombosis in a patient with prolonged immobilisation after surgery?

  1. Stasis and hypercoagulability Correct answer.
  2. Hypercoagulability alone
  3. Endothelial injury and stasis
  4. Endothelial injury and hypercoagulability

Explanation

Prolonged immobilisation causes venous stasis, and surgery induces a postoperative hypercoagulable state through increased clotting factors and reduced fibrinolysis. Together, stasis and hypercoagulability are the dominant contributors to deep vein thrombosis in this setting. Endothelial injury is more important in arterial thrombosis over atherosclerotic plaques.

Question 31Systemic Pathology (organ-based non-neoplastic disease)

A 45-year-old man presents with nephrotic-range proteinuria. Renal biopsy shows diffuse thickening of glomerular capillary walls with spike-and-dome subepithelial deposits on silver stain and IgG/C3 granular deposits on immunofluorescence. Which diagnosis is most likely?

  1. Membranous nephropathy Correct answer.
  2. Minimal change disease
  3. Post-infectious glomerulonephritis
  4. IgA nephropathy

Explanation

Membranous nephropathy characteristically produces subepithelial immune deposits that create spike-and-dome patterns on silver stain with granular IgG and C3 along capillary loops, and it is a common cause of nephrotic syndrome in middle-aged adults. The other entities have different deposit locations or light microscopy findings.

Question 32Systemic Pathology (organ-based non-neoplastic disease)

A 62-year-old woman with long-standing type 2 diabetes has progressive renal impairment and heavy proteinuria. Biopsy shows nodular mesangial expansion with Kimmelstiel-Wilson nodules and linear IgG staining along capillary basement membranes. What is the most likely diagnosis?

  1. Diabetic nephropathy Correct answer.
  2. Membranoproliferative glomerulonephritis
  3. Light chain deposition disease
  4. Amyloidosis

Explanation

Nodular glomerulosclerosis with Kimmelstiel-Wilson nodules and linear IgG staining due to non-specific trapping in thickened basement membranes is the hallmark of diabetic nephropathy. The clinical context of long-standing diabetes with proteinuria supports this diagnosis.

Question 33Systemic Pathology (organ-based non-neoplastic disease)

A 30-year-old woman has hypertension, hematuria, and rising creatinine. Renal biopsy shows crescents filling Bowman's space in most glomeruli. Which process do these crescents primarily represent?

  1. Proliferation of parietal epithelial cells and macrophages Correct answer.
  2. Amyloid deposition
  3. Mesangial IgA deposition
  4. Subepithelial immune complex deposition

Explanation

Crescents in rapidly progressive glomerulonephritis result from proliferation of parietal epithelial cells together with monocytes and macrophages, often with fibrin exudation into Bowman's space. They compress the glomerular tuft and cause rapid loss of renal function.

Question 34Systemic Pathology (organ-based non-neoplastic disease)

A 55-year-old man with chronic hepatitis B develops nephrotic syndrome. Biopsy shows thickened capillary walls with subepithelial deposits and some mesangial interposition. Which virus is most strongly associated with this membranous pattern?

  1. Epstein-Barr virus
  2. Hepatitis A virus
  3. Hepatitis B virus Correct answer.
  4. Hepatitis E virus

Explanation

Hepatitis B virus is a well-established cause of secondary membranous nephropathy, particularly in endemic areas, through immune complex deposition containing viral antigens. This association is important to recognize because antiviral therapy can improve the renal disease.

Question 35Systemic Pathology (organ-based non-neoplastic disease)

A 68-year-old man with a 40 pack-year smoking history presents with hematuria and a renal mass. Histology shows nests of cells with abundant clear cytoplasm and a delicate branching capillary network. Which renal tumor is most likely?

  1. Chromophobe renal cell carcinoma
  2. Papillary renal cell carcinoma
  3. Renal oncocytoma
  4. Clear cell renal cell carcinoma Correct answer.

Explanation

Clear cell renal cell carcinoma is characterized by nests of cells with optically clear cytoplasm due to glycogen and lipid content, supported by a delicate arborizing capillary network. It is the most common renal cell carcinoma and is associated with smoking.

Question 36Systemic Pathology (organ-based non-neoplastic disease)

A 3-year-old boy presents with a large abdominal mass. Imaging shows a renal tumor, and histology shows a triphasic pattern of blastema, epithelium, and stroma. Which diagnosis is most likely?

  1. Wilms tumor Correct answer.
  2. Neuroblastoma
  3. Clear cell sarcoma of kidney
  4. Renal medullary carcinoma

Explanation

Wilms tumor (nephroblastoma) is the most common pediatric renal tumor and classically shows a triphasic histology of blastemal, epithelial, and stromal components. It typically presents as a large abdominal mass in children under 5 years.

Question 37Systemic Pathology (organ-based non-neoplastic disease)

A 70-year-old man presents with painless gross hematuria. Cystoscopy reveals a papillary bladder mass. Histology shows papillary fronds lined by urothelial cells with mild atypia and intact polarity. Which diagnosis is most likely?

  1. Urothelial carcinoma in situ
  2. Squamous cell carcinoma of the bladder
  3. Non-invasive papillary urothelial carcinoma, low grade Correct answer.
  4. Adenocarcinoma of the bladder

Explanation

Non-invasive papillary urothelial carcinoma, low grade, shows papillary architecture with orderly urothelial cells and mild atypia. It typically presents with painless hematuria and has a tendency to recur rather than invade.

Question 38Systemic Pathology (organ-based non-neoplastic disease)

A 60-year-old man with recurrent calcium oxalate stones undergoes nephrectomy for a non-functioning kidney. Histology shows dilated tubules filled with laminated calcified concretions and chronic interstitial inflammation. What is the most likely diagnosis?

  1. Xanthogranulomatous pyelonephritis
  2. Acute tubular necrosis
  3. Chronic pyelonephritis with nephrolithiasis Correct answer.
  4. Renal papillary necrosis

Explanation

Chronic pyelonephritis with nephrolithiasis shows dilated tubules containing laminated calcified concretions (stones), tubular atrophy, and chronic interstitial inflammation. Recurrent obstruction and infection lead to progressive scarring and loss of renal parenchyma.

Question 39Systemic Pathology (organ-based non-neoplastic disease)

A 35-year-old woman has recurrent urinary tract infections. Imaging shows a unilateral enlarged, scarred kidney with caliceal blunting and cortical thinning. Which pathogen is most commonly associated with uncomplicated community-acquired pyelonephritis?

  1. Pseudomonas aeruginosa
  2. Staphylococcus saprophyticus
  3. Proteus mirabilis
  4. Escherichia coli Correct answer.

Explanation

Escherichia coli is the most common cause of uncomplicated community-acquired urinary tract infection and pyelonephritis, accounting for the majority of cases. Its uropathogenic strains express adhesins such as P fimbriae that facilitate ascending infection.

Question 40Systemic Pathology (organ-based non-neoplastic disease)

A 50-year-old woman has a 2 cm renal cortical lesion removed. Histology shows a well-circumscribed tumor composed of nests of large cells with abundant eosinophilic granular cytoplasm and central scar-like areas. Which diagnosis is most likely?

  1. Clear cell renal cell carcinoma
  2. Transitional cell carcinoma
  3. Renal oncocytoma Correct answer.
  4. Angiomyolipoma

Explanation

Renal oncocytoma is a benign cortical tumor composed of nests of large cells with abundant eosinophilic granular cytoplasm, often with a central stellate scar. It is important to distinguish it from chromophobe renal cell carcinoma, which can show similar cells.

Question 41Systemic Pathology (organ-based non-neoplastic disease)

A 40-year-old man with a history of treated syphilis develops nephrotic syndrome. Renal biopsy shows membranous pattern with prominent mesangial interposition and tram-track appearance on silver stain. Which secondary cause is most likely?

  1. Malaria infection
  2. Hepatitis C infection
  3. Syphilis infection Correct answer.
  4. Schistosomiasis

Explanation

Secondary syphilis is a recognized cause of membranous nephropathy, which can show mesangial interposition and tram-track changes. Recognizing infectious causes is important because treatment of the underlying infection may improve the renal lesion.

Question 42Systemic Pathology (organ-based non-neoplastic disease)

A 25-year-old man presents with hematuria and flank pain after an upper respiratory infection. Renal biopsy shows mesangial hypercellularity with IgA deposits on immunofluorescence. Which mechanism best explains the hematuria?

  1. Mesangial immune complex deposition and inflammation Correct answer.
  2. Amyloid fibril deposition in glomeruli
  3. Complement-mediated glomerular basement membrane damage
  4. Direct viral infection of podocytes

Explanation

IgA nephropathy is caused by mesangial deposition of IgA-containing immune complexes, which triggers local inflammation and mesangial proliferation. This leads to hematuria, often after mucosal infections.

Question 43Systemic Pathology (organ-based non-neoplastic disease)

A 65-year-old man with chronic kidney disease has a renal biopsy showing extensive interstitial fibrosis, tubular atrophy, and sclerotic glomeruli. Which term best describes this final common pathway of progressive renal injury?

  1. Acute tubular necrosis
  2. Minimal change disease
  3. Renal papillary necrosis
  4. End-stage renal disease Correct answer.

Explanation

End-stage renal disease represents the final common pathway of chronic kidney disease, characterized by extensive interstitial fibrosis, tubular atrophy, and glomerulosclerosis. It reflects irreversible loss of renal parenchyma regardless of the initial cause.

Question 44Systemic Pathology (organ-based non-neoplastic disease)

A 28-year-old woman with systemic lupus erythematosus develops proteinuria and hematuria. Renal biopsy shows diffuse wire-loop lesions and subendothelial immune deposits. Which class of lupus nephritis does this represent?

  1. Class III focal proliferative
  2. Class IV diffuse proliferative Correct answer.
  3. Class V membranous
  4. Class II mesangial proliferative

Explanation

Class IV diffuse proliferative lupus nephritis involves more than 50% of glomeruli and characteristically shows wire-loop lesions from subendothelial immune deposits. It is the most severe form and requires aggressive immunosuppression.

Question 45Systemic Pathology (organ-based non-neoplastic disease)

A 55-year-old man with long-standing hypertension dies of a stroke. At autopsy, the kidneys are symmetrically shrunken with a finely granular surface. Histology shows hyaline arteriolosclerosis and ischemic glomerular changes. Which diagnosis is most likely?

  1. Renal artery stenosis
  2. Benign nephrosclerosis Correct answer.
  3. Malignant hypertension
  4. Chronic glomerulonephritis

Explanation

Benign nephrosclerosis results from chronic hypertension and produces symmetrically shrunken kidneys with a finely granular surface, hyaline arteriolosclerosis, and ischemic glomerular changes. It is a common cause of chronic kidney disease in older adults.

Question 46Systemic Pathology (organ-based non-neoplastic disease)

A 45-year-old woman has a history of recurrent kidney stones and medullary sponge kidney. Which complication is most directly related to chronic obstruction and infection in this setting?

  1. Minimal change disease
  2. Renal cell carcinoma
  3. Chronic pyelonephritis Correct answer.
  4. Membranous nephropathy

Explanation

Chronic obstruction and infection, as seen with recurrent stones and medullary sponge kidney, predispose to chronic pyelonephritis with scarring and tubular damage. This can progress to chronic kidney disease.

Question 47Systemic Pathology (organ-based non-neoplastic disease)

A 70-year-old man presents with hematuria and a renal pelvic mass. Histology shows a papillary urothelial neoplasm with high-grade nuclear atypia and invasion into the renal parenchyma. Which diagnosis is most likely?

  1. Urothelial carcinoma of the renal pelvis Correct answer.
  2. Renal cell carcinoma
  3. Renal oncocytoma
  4. Wilms tumor

Explanation

Urothelial carcinoma of the renal pelvis arises from the urothelial lining and often presents with hematuria and a renal pelvic mass. It can show papillary architecture and high-grade atypia with invasion into the kidney.

Question 48Systemic Pathology (organ-based non-neoplastic disease)

A 30-year-old woman has nephrotic syndrome. Renal biopsy shows focal segmental glomerulosclerosis (FSGS). Which finding is most characteristic of primary FSGS?

  1. Mesangial IgA deposits
  2. Subepithelial immune deposits
  3. Linear IgG along basement membranes
  4. Diffuse foot process effacement on electron microscopy Correct answer.

Explanation

Primary FSGS shows focal and segmental sclerosis on light microscopy and diffuse foot process effacement on electron microscopy. The diffuse effacement reflects a circulating permeability factor affecting podocytes.

Question 49Systemic Pathology (organ-based non-neoplastic disease)

A 55-year-old man with diabetes develops acute renal failure and fever. Imaging shows a swollen kidney with a mass-like lesion. Histology shows lipid-laden macrophages and chronic inflammation surrounding a staghorn calculus. Which diagnosis is most likely?

  1. Renal cell carcinoma
  2. Acute pyelonephritis
  3. Renal papillary necrosis
  4. Xanthogranulomatous pyelonephritis Correct answer.

Explanation

Xanthogranulomatous pyelonephritis is a chronic inflammatory condition characterized by lipid-laden macrophages and a mass-like lesion, often associated with a staghorn calculus and diabetes. It can mimic renal cell carcinoma clinically.

Question 50Systemic Pathology (organ-based non-neoplastic disease)

A 40-year-old man has nephrotic syndrome and a renal biopsy showing thickened capillary walls with subepithelial deposits. Immunofluorescence shows granular IgG and C3. Which antigen is most commonly targeted in primary membranous nephropathy?

  1. IgA
  2. Goodpasture antigen
  3. Phospholipase A2 receptor Correct answer.
  4. Double-stranded DNA

Explanation

Primary membranous nephropathy is most commonly associated with autoantibodies against the phospholipase A2 receptor (PLA2R) on podocytes. This is a key diagnostic marker and helps distinguish primary from secondary forms.