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Arab Board Anatomic Pathology Part 1 study materials
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Arab Board Anatomic Pathology Part 1 practice questions

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

Which morphologic change is the earliest light-microscopic sign of reversible cell injury?

  1. Plasma membrane rupture
  2. Dystrophic calcification
  3. Cellular swelling Correct answer.
  4. Nuclear fragmentation

Explanation

In reversible cell injury, failure of the Na+/K+ ATPase causes sodium and water influx, so cellular swelling is the earliest light-microscopic change. Nuclear fragmentation and plasma membrane rupture indicate irreversible injury and necrosis. Dystrophic calcification occurs later in damaged tissues.

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

A cerebral infarct caused by arterial occlusion typically undergoes which type of necrosis?

  1. Coagulative necrosis of solid organs
  2. Caseous necrosis in tuberculosis
  3. Fat necrosis after pancreatitis
  4. Liquefactive necrosis Correct answer.

Explanation

Brain tissue is rich in enzymes and undergoes liquefactive necrosis after infarction, leaving a cystic cavity. Coagulative necrosis is typical of ischemic infarction in heart, kidney, and spleen. Caseous necrosis occurs in tuberculosis, and fat necrosis follows pancreatic or traumatic injury.

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

Which family of enzymes executes the apoptotic program?

  1. Myeloperoxidases
  2. Complement convertases
  3. Caspases Correct answer.
  4. Matrix metalloproteinases

Explanation

Caspases are cysteine proteases that cleave key cellular substrates during apoptosis. Matrix metalloproteinases degrade extracellular matrix, myeloperoxidases generate microbicidal oxidants, and complement convertases assemble the complement cascade.

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

Which leukocyte is typically the first to migrate into an acute inflammatory site?

  1. Eosinophil
  2. Neutrophil Correct answer.
  3. Lymphocyte
  4. Macrophage

Explanation

Neutrophils are the first leukocytes recruited in acute inflammation, arriving within minutes to hours. Macrophages follow and predominate later, while lymphocytes and eosinophils are characteristic of chronic or allergic inflammation.

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

Chronic inflammation is characterized by infiltration of which cell pair?

  1. Neutrophils and eosinophils
  2. Macrophages and lymphocytes Correct answer.
  3. Plasma cells and neutrophils
  4. Mast cells and basophils

Explanation

Chronic inflammation features macrophages and lymphocytes, often with plasma cells and fibrosis. Neutrophils and eosinophils dominate acute or allergic responses, and mast cells and basophils mediate immediate hypersensitivity.

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

Which wound is expected to heal by secondary intention?

  1. A small punch biopsy closed with adhesive
  2. A clean surgical incision approximated with sutures
  3. A superficial abrasion with intact epithelium
  4. An infected wound with a wide tissue gap Correct answer.

Explanation

Secondary intention occurs when wound edges cannot be approximated, as in infected or widely gaping wounds. It produces abundant granulation tissue, wound contraction, and a larger scar than primary intention. Clean sutured incisions heal by primary intention.

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

A benign tumor arising from glandular epithelium is called:

  1. Papilloma
  2. Adenocarcinoma
  3. Adenoma Correct answer.
  4. Sarcoma

Explanation

A benign epithelial tumor of glandular origin is an adenoma. Adenocarcinoma is malignant glandular epithelium, papilloma is a benign surface epithelial tumor, and sarcoma arises from mesenchyme.

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

Which factor is a component of Virchow triad for thrombosis?

  1. Nephrotic syndrome with hypoalbuminemia
  2. Chronic iron deficiency anemia
  3. Endothelial injury Correct answer.
  4. Severe thrombocytopenia with petechiae

Explanation

Virchow triad comprises endothelial injury, abnormal blood flow (stasis or turbulence), and hypercoagulability. Thrombocytopenia and hypoalbuminemia predispose to bleeding or edema rather than thrombosis. Anemia does not directly promote thrombosis.

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

Which mechanism contributes most to ischemia-reperfusion injury after blood flow is restored?

  1. Generation of reactive oxygen species Correct answer.
  2. Loss of mitochondrial membrane potential
  3. Activation of caspases by cytochrome c
  4. Influx of calcium during ischemia

Explanation

Reperfusion restores oxygen, which drives xanthine oxidase and neutrophil-generated reactive oxygen species and can trigger complement activation. These mediators damage membranes and mitochondria. Caspase activation and calcium influx contribute to injury but are not the specific reperfusion burst.

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

Chalky white deposits in the peripancreatic fat in acute pancreatitis result from:

  1. Coagulative necrosis of adipocytes
  2. Fibrinoid necrosis of vessel walls
  3. Fat saponification Correct answer.
  4. Caseous necrosis with granulomas

Explanation

Pancreatic lipases release fatty acids that bind calcium, producing chalky fat saponification in peripancreatic fat. Coagulative necrosis affects parenchymal cells, caseous necrosis occurs in tuberculosis, and fibrinoid necrosis affects vessel walls.

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

Release of which mitochondrial molecule activates the caspase cascade in apoptosis?

  1. Complement C3b
  2. Catalase
  3. Fibrinogen
  4. Cytochrome c Correct answer.

Explanation

Cytochrome c released from mitochondria binds Apaf-1 and activates caspase-9, initiating the intrinsic apoptotic pathway. Catalase detoxifies hydrogen peroxide, C3b is an opsonin, and fibrinogen is a clotting protein.

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

Which adhesion molecule mediates firm adhesion of neutrophils to endothelium?

  1. P-selectin glycoprotein ligand-1
  2. Integrins Correct answer.
  3. Selectins
  4. ICAM-1

Explanation

Integrins on leukocytes bind endothelial ICAM-1 to mediate firm adhesion after selectin-dependent rolling. Selectins mediate rolling, and PSGL-1 is a selectin ligand. ICAM-1 is the endothelial counter-receptor, not the leukocyte integrin.

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

Which mediator is preformed in mast cell granules and causes immediate vasodilation and increased vascular permeability?

  1. Histamine Correct answer.
  2. Prostaglandin E2
  3. Leukotriene B4
  4. Interleukin-1

Explanation

Histamine is stored in mast cell granules and causes immediate vasodilation and endothelial gap formation. Prostaglandins and leukotrienes are synthesized after mast cell activation, and interleukin-1 is a cytokine.

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

The characteristic cell of a granuloma is:

  1. Epithelioid macrophage Correct answer.
  2. Neutrophil with multilobed nucleus
  3. Plasma cell with clock-face nucleus
  4. Eosinophil with bilobed nucleus

Explanation

Granulomas consist of epithelioid macrophages, often with multinucleated giant cells and a rim of lymphocytes. Neutrophils, eosinophils, and plasma cells may be present but are not the defining cell.

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

Granulation tissue is composed mainly of:

  1. Adipose tissue with abundant elastic fibers and vessels
  2. Capillaries, fibroblasts, and inflammatory cells Correct answer.
  3. Dense collagen bundles with very few fibroblasts and vessels
  4. Mature bone and cartilage with fatty marrow spaces

Explanation

Granulation tissue contains proliferating capillaries, fibroblasts, and inflammatory cells. It fills wounds before maturation into collagen-rich scar. Dense collagen, bone, cartilage, and adipose tissue are features of mature or specialized tissues.

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

The p53 gene product normally functions to:

  1. Stimulate angiogenesis by secreting VEGF
  2. Activate telomerase and immortalize cells
  3. Promote G1/S transition and cell cycle entry
  4. Induce cell cycle arrest after DNA damage Correct answer.

Explanation

p53 is a tumor suppressor that arrests the cell cycle to allow DNA repair or triggers apoptosis when damage is severe. Loss of p53 permits survival of mutated cells. It does not promote cell cycle entry, telomerase activation, or angiogenesis.

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

Carcinomas most commonly first metastasize through which route?

  1. Peritoneal fluid
  2. Cerebrospinal fluid
  3. Bile ducts
  4. Lymphatic channels Correct answer.

Explanation

Carcinomas usually metastasize first via lymphatics, whereas sarcomas spread mainly hematogenously. Cerebrospinal fluid, peritoneal fluid, and bile ducts are not common primary routes.

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

Which tumor marker is typically elevated in hepatocellular carcinoma and yolk sac tumors?

  1. CA 19-9, a pancreatic marker
  2. Prostate-specific antigen
  3. Carcinoembryonic antigen
  4. Alpha-fetoprotein Correct answer.

Explanation

Alpha-fetoprotein is elevated in hepatocellular carcinoma and yolk sac tumors. CA 19-9, CEA, and PSA are associated with pancreatic, colorectal, and prostate carcinomas, respectively.

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

Which feature is characteristic of an arterial thrombus formed in flowing blood?

  1. Liquefactive necrosis
  2. Caseous granuloma
  3. Fat saponification
  4. Lines of Zahn Correct answer.

Explanation

Lines of Zahn are alternating pale platelet-fibrin layers and dark red cell layers, indicating a thrombus formed in flowing blood. Liquefactive necrosis, caseous granulomas, and fat saponification are unrelated lesions.

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

Most pulmonary emboli originate from:

  1. Left atrial appendage
  2. Inferior vena cava thrombosis above renal veins
  3. Aortic atherosclerosis
  4. Deep veins of the lower extremities Correct answer.

Explanation

Most pulmonary emboli arise from deep venous thrombosis of the lower extremities, especially above the knee. Left atrial thrombi embolize systemically, and aortic atherosclerosis causes arterial emboli.

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

Opening of the mitochondrial permeability transition pore in ischemic cell injury leads to:

  1. Activation of receptor tyrosine kinases by growth factors
  2. Enhanced DNA repair after oxidative damage
  3. Loss of membrane potential and ATP production Correct answer.
  4. Increased ATP synthesis by oxidative phosphorylation

Explanation

The mitochondrial permeability transition pore allows small molecules to enter mitochondria, collapsing membrane potential and halting ATP synthesis. This is a key event in irreversible ischemic injury. It does not increase ATP synthesis, activate receptor tyrosine kinases, or enhance DNA repair.

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

Which complement fragment is the most potent chemotactic factor for neutrophils?

  1. C5a Correct answer.
  2. C3a
  3. C3b
  4. C5b

Explanation

C5a is a potent neutrophil chemoattractant and anaphylatoxin. C3a is an anaphylatoxin with weak chemotactic activity, C3b is an opsonin, and C5b initiates the membrane attack complex.

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

The t(8;14) translocation in Burkitt lymphoma leads to overexpression of which oncogene?

  1. BCL2
  2. ABL1
  3. MYC Correct answer.
  4. RAS

Explanation

The t(8;14) translocation places MYC under immunoglobulin heavy-chain enhancer control, causing overexpression in Burkitt lymphoma. BCL2 is activated in follicular lymphoma, ABL1 in chronic myeloid leukemia, and RAS by point mutation.

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

Disseminated intravascular coagulation is characterized by:

  1. Selective inherited deficiency of protein C
  2. Widespread microthrombi and factor consumption Correct answer.
  3. Isolated large-vein thrombosis without any bleeding
  4. Increased platelet count with elevated clotting factors

Explanation

DIC causes widespread microthrombi that consume platelets and clotting factors, leading to both thrombosis and hemorrhage. It is not isolated large-vein thrombosis, thrombocytosis, or selective protein C deficiency.

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

Which tissue has the greatest capacity for regeneration after injury?

  1. Cardiac muscle with permanent cells
  2. Skeletal muscle with satellite cells
  3. Hepatic epithelium Correct answer.
  4. Cortical neurons of the cerebral cortex

Explanation

Hepatocytes are stable cells that remain in G0 but re-enter the cell cycle after injury, allowing hepatic regeneration. Cardiac myocytes and cortical neurons are permanent cells, and skeletal muscle regenerates poorly despite satellite cells.

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

Which change is the earliest morphologic sign of reversible cell injury?

  1. Cellular swelling Correct answer.
  2. Plasma membrane rupture
  3. Nuclear fragmentation
  4. Mitochondrial calcification

Explanation

Reversible cell injury begins with ATP depletion and failure of the sodium-potassium pump, causing sodium and water influx. The resulting cellular swelling is the earliest light-microscopic change, whereas nuclear fragmentation and membrane rupture indicate irreversible injury.

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

Which vascular change is responsible for the earliest visible redness in acute inflammation?

  1. Increased lymphatic drainage
  2. Fibrin deposition
  3. Vasodilation Correct answer.
  4. Neutrophilic infiltration

Explanation

Arteriolar vasodilation increases local blood flow and produces the redness and warmth of acute inflammation. This vascular phase precedes the cellular events of neutrophil margination and migration.

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

Which property most reliably distinguishes a malignant from a benign epithelial tumor?

  1. Uniform cell size
  2. Slow growth rate
  3. Presence of a fibrous capsule
  4. Metastasis to distant sites Correct answer.

Explanation

The defining feature of malignancy is the ability to invade and metastasize, whereas benign epithelial tumors remain localized. Slow growth, encapsulation, and uniform cells can be seen in benign lesions and do not prove malignancy.

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

Which condition results from increased hydrostatic pressure in the pulmonary capillaries?

  1. Left-sided heart failure Correct answer.
  2. Severe hypoalbuminemia from nephrotic syndrome
  3. Bilateral lymphatic obstruction
  4. Primary sodium retention by the kidney

Explanation

Left-sided heart failure raises pulmonary capillary hydrostatic pressure, favoring transudation of fluid into alveoli. Hypoalbuminemia and lymphatic obstruction cause edema by different Starling mechanisms.

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

A 60-year-old man with chronic renal failure has calcium deposits in normal skin and blood vessels. Serum calcium is normal. Which process explains these deposits?

  1. Apoptotic body formation
  2. Dystrophic calcification Correct answer.
  3. Metastatic calcification
  4. Heterotopic ossification

Explanation

Dystrophic calcification occurs in damaged or necrotic tissue despite normal serum calcium levels. It is common in chronic renal injury, atheromas, and old scars; metastatic calcification, by contrast, follows hypercalcemia.

Question 31General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which process enhances phagocytosis by coating a microbe with immunoglobulin G and complement C3b?

  1. Margination
  2. Diapedesis
  3. Chemotaxis
  4. Opsonization Correct answer.

Explanation

Opsonization is the coating of microbes with opsonins such as IgG and C3b, which are recognized by phagocyte receptors. This markedly enhances recognition and engulfment.

Question 32General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

During healing of a clean surgical incision, which collagen type is laid down first and later replaced by stronger type I collagen?

  1. Type I
  2. Type IV
  3. Type II
  4. Type III Correct answer.

Explanation

Type III collagen is deposited as a provisional matrix during granulation tissue formation. As healing progresses, it is replaced by stronger type I collagen through remodeling.

Question 33General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which feature indicates carcinoma in situ rather than invasive carcinoma?

  1. Lymphatic invasion of regional nodes
  2. Intact basement membrane Correct answer.
  3. Distant metastasis to bone
  4. Vascular invasion of local veins

Explanation

Carcinoma in situ shows full-thickness epithelial atypia but the basement membrane remains intact, so there is no invasion. Vascular or lymphatic invasion and distant spread define invasive carcinoma.

Question 34General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A 25-year-old man develops dyspnea and petechiae 48 hours after a femur fracture. Which embolism is most likely?

  1. Amniotic fluid embolism
  2. Air embolism
  3. Fat embolism Correct answer.
  4. Thromboembolism

Explanation

After long-bone fracture, marrow fat can enter torn venules and embolize to the lungs. The classic triad is respiratory distress, petechiae, and neurologic symptoms occurring one to three days after injury.

Question 35General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Barrett esophagus is characterized by replacement of stratified squamous epithelium by columnar epithelium. This is an example of:

  1. Hyperplasia
  2. Dysplasia
  3. Metaplasia Correct answer.
  4. Neoplasia

Explanation

Metaplasia is a reversible change in which one mature epithelial type is replaced by another that better tolerates stress. In Barrett esophagus, chronic acid reflux induces columnar epithelium in the distal esophagus.

Question 36General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A child has recurrent bacterial infections, delayed separation of the umbilical cord, and absent pus formation. Which defect is most likely?

  1. Myeloperoxidase deficiency
  2. Complement C5 deficiency
  3. CD18 integrin defect Correct answer.
  4. NADPH oxidase deficiency

Explanation

Leukocyte adhesion deficiency type 1 results from defective CD18 integrin, impairing firm adhesion and transmigration of neutrophils. Affected children have recurrent bacterial infections, delayed umbilical cord separation, and poor pus formation.

Question 37General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A keloid differs from a hypertrophic scar because a keloid:

  1. Regresses spontaneously over months
  2. Remains confined to the original wound
  3. Contains no detectable collagen
  4. Extends beyond the wound margins Correct answer.

Explanation

A keloid is excessive collagenous scar that extends beyond the original wound margins. A hypertrophic scar remains confined to the wound and often regresses.

Question 38General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which genetic alteration is most characteristic of hereditary retinoblastoma?

  1. Translocation t(8;14) involving MYC
  2. Activating point mutation of RAS
  3. Amplification of MYCN in tumor cells
  4. Germline RB mutation plus somatic loss Correct answer.

Explanation

Hereditary retinoblastoma follows the two-hit model: a germline RB mutation is present in all cells, and a somatic second hit in a retinal cell abolishes the remaining functional allele. Loss of RB releases E2F and permits uncontrolled G1-to-S transition.

Question 39General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

A patient has recurrent Neisseria infections. Which complement defect is most likely?

  1. C1 inhibitor deficiency
  2. Factor H deficiency
  3. C5-C9 deficiency Correct answer.
  4. C3 deficiency

Explanation

Deficiency of terminal complement components C5 through C9 prevents formation of the membrane attack complex, causing recurrent Neisseria infections. C3 deficiency causes recurrent pyogenic infections, and C1 inhibitor deficiency causes hereditary angioedema.

Question 40General pathology (cell injury, inflammation, repair, neoplasia, hemodynamics)

Which type of infarct is most likely after venous occlusion in the lung?

  1. White infarct
  2. Fibrinoid necrosis
  3. Caseous necrosis
  4. Red infarct Correct answer.

Explanation

The lung has a dual blood supply and loose, spongy tissue, so venous occlusion produces hemorrhage into the infarcted area. Such infarcts are red (hemorrhagic) rather than pale.

Question 41Systemic pathology by organ system

A 55-year-old man with chronic gastroesophageal reflux undergoes endoscopy, and biopsy of the distal esophagus shows columnar epithelium containing goblet cells. What is the most appropriate diagnosis?

  1. Barrett esophagus with intestinal metaplasia Correct answer.
  2. Eosinophilic esophagitis
  3. Squamous cell carcinoma in situ
  4. Squamous hyperplasia from achalasia

Explanation

Columnar metaplasia containing goblet cells is intestinal metaplasia, the defining histologic feature of Barrett esophagus. It develops as a response to chronic acid reflux and raises the risk of esophageal adenocarcinoma. Identification triggers consideration of surveillance endoscopy.

Question 42Systemic pathology by organ system

A thyroid fine-needle aspirate shows cells with optically clear nuclei, nuclear grooves, and intranuclear pseudoinclusions. Which diagnosis is most likely?

  1. Anaplastic thyroid carcinoma
  2. Medullary thyroid carcinoma
  3. Papillary thyroid carcinoma Correct answer.
  4. Follicular adenoma

Explanation

Optically clear nuclei, grooves, and pseudoinclusions are the nuclear hallmarks of papillary thyroid carcinoma. Psammoma bodies and papillary architecture may also be present. These nuclear features remain diagnostic even when the growth pattern is follicular.

Question 43Systemic pathology by organ system

Which histologic finding is required to establish the diagnosis of acute appendicitis?

  1. Fibrosis of the serosa with chronic inflammation
  2. Lymphoid follicular hyperplasia alone
  3. Goblet cell hyperplasia of the mucosa
  4. Neutrophils within the muscularis propria Correct answer.

Explanation

Acute appendicitis is defined by neutrophilic infiltration that extends into the muscularis propria. Mucosal neutrophils alone can occur with reactive or early changes and are insufficient for the diagnosis. Serosal inflammation may accompany but is not the defining feature.

Question 44Systemic pathology by organ system

Which feature is the strongest predictor of survival in a patient with a primary cutaneous melanoma?

  1. Anatomical site of the lesion
  2. Breslow thickness in millimeters Correct answer.
  3. Patient age at diagnosis
  4. Radial growth phase

Explanation

Breslow thickness, measured from the granular layer to the deepest tumor cell, is the single strongest prognostic factor in localized melanoma. Ulceration and mitotic rate provide additional prognostic information. Depth reflects the likelihood of metastatic spread.

Question 45Systemic pathology by organ system

Which is the most common malignant renal tumor in adults?

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

Explanation

Clear cell renal cell carcinoma accounts for roughly 70 to 80 percent of adult renal malignancies. It typically shows nests of cells with clear cytoplasm and a delicate branching vasculature. Papillary and chromophobe carcinomas are less common subtypes.

Question 46Systemic pathology by organ system

In which zone of the prostate do most adenocarcinomas arise?

  1. Periurethral zone
  2. Transition zone
  3. Central zone
  4. Peripheral zone Correct answer.

Explanation

About 70 percent of prostate adenocarcinomas arise in the peripheral zone, which is why they are often palpable on digital rectal examination. Benign prostatic hyperplasia preferentially involves the transition zone. This anatomic distribution guides biopsy sampling.

Question 47Systemic pathology by organ system

A dural-based extra-axial mass in a middle-aged woman shows whorls of meningothelial cells and psammoma bodies. Which diagnosis is most likely?

  1. Meningioma Correct answer.
  2. Schwannoma
  3. Metastatic adenocarcinoma
  4. Glioblastoma

Explanation

Whorl formation and psammoma bodies in a dural-based extra-axial tumor are classic for meningioma, most often WHO grade 1. These tumors are typically well circumscribed and epithelial membrane antigen positive. They compress rather than invade the underlying brain.

Question 48Systemic pathology by organ system

Which human papillomavirus types account for most cervical squamous cell carcinomas?

  1. HPV 53 and 66
  2. HPV 6 and 11
  3. HPV 42 and 43
  4. HPV 16 and 18 Correct answer.

Explanation

High-risk HPV 16 and 18 cause the majority of cervical squamous cell carcinomas and are the types targeted by prophylactic vaccines. Viral E6 and E7 proteins inactivate p53 and Rb, driving malignant transformation. Low-risk types such as 6 and 11 cause condylomata but rarely carcinoma.

Question 49Systemic pathology by organ system

A 28-year-old woman has recurrent abdominal pain and diarrhea. Colonoscopy shows skip lesions with deep linear ulcers, and biopsy shows transmural inflammation with non-caseating granulomas. Which diagnosis is most likely?

  1. Ischemic colitis
  2. Crohn disease Correct answer.
  3. Ulcerative colitis
  4. Microscopic colitis

Explanation

Transmural inflammation, skip lesions, and non-caseating granulomas favor Crohn disease. Ulcerative colitis instead produces continuous mucosal disease limited to the colon. The transmural nature of Crohn disease explains fistula and stricture formation.

Question 50Systemic pathology by organ system

A child with failure to thrive has positive anti-tissue transglutaminase antibodies, and duodenal biopsy shows villous blunting, crypt hyperplasia, and increased intraepithelial lymphocytes. Which diagnosis fits best?

  1. Whipple disease
  2. Giardiasis
  3. Celiac disease Correct answer.
  4. Tropical sprue

Explanation

Villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis in a patient with positive anti-tissue transglutaminase antibodies are diagnostic of celiac disease. Removal of gluten from the diet leads to mucosal recovery. Serology and histology together establish the diagnosis.