USMLE Step 1 Pathology Questions with Answers (95 High-Yield MCQs)

These 95 USMLE Step 1 pathology practice questions cover the diseases, histology findings and lab clues that appear again and again on the exam. They are organized by organ system so you can study one topic at a time. Every question includes the correct answer and a short explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then click Show Answer and Explanation. Read the explanation even when you are right — repeated question types are common on the real exam.

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General Pathology: Cell Injury, Inflammation and Neoplasia

Question 1. Which of the following symptoms is more commonly associated with allergies rather than the common cold?

A- Fever
B- Runny nose
C- Sore throat
D- Watery eyes

D- Watery eyes- Watery eyes are more commonly associated with allergies rather than the common cold. While both allergies and the common cold can cause symptoms such as a sore throat, runny nose, and occasionally fever, itchy watery eyes are a hallmark symptom of allergic rhinitis (hay fever) triggered by allergens such as pollen, dust mites, or pet dander. Itchy eyes are not typically a prominent symptom of the common cold, which is primarily characterized by nasal congestion, sneezing, and a runny nose.

 

Question 2. A 13-year-old boy presents with multiple episodes of ear pain and fever. Examination reveals a red and bulging right tympanic membrane with yellow exudate. Laboratory studies confirm culture positive for Hemophilus influenzae. Six months later, he develops conductive hearing loss on the right. A head CT scan shows a mass in the right middle ear. What material is most likely to be observed in the tissue collected from his middle ear?

A- Anthracitic pigment
B- Cholesterol crystals
C- Lipofuscin pigment
D- Neutrophil granules

B- Cholesterol crystals- This is a typical case of chronic otitis media with effusion. Cholesterol crystals are commonly found in tissue debris associated with this condition. They result from the breakdown of red blood cells and lipid-rich cellular debris in the middle ear space over time.

 

Question 3. A newborn is evaluated at birth due to congenital malformation. FISH analysis shows 22q 11.2 microdeletion. Which of the following is the most likely diagnosis?

A- Achondroplasia
B- DiGeorge syndrome
C- Down syndrome
D- Turner syndrome

B– DiGeorge syndrome- This deletion causes abnormal fetal development of the 3rd and 4th pharyngeal pouches. It affects the thymus and parathyroid gland.

 

Question 4. Which one of the following may precipitate to an acute porphyria attack?

A- High-carbohydrate diet
B- Low-carbohydrate diet
C- Mediterranean diet
D- Vegetarian diet

B- Low-carbohydrate diet- Low low-calorie, low-carbohydrate diet may precipitate to acute attack. In contrast, high high-carbohydrate diet may decrease the risk of an acute attack.

 

Question 5. A young man was stuck on his leg by a falling rack a week ago. Today, a purple bruise developed on the site of injury. Which one of the following substances is responsible for the color at the site of injury?

A- Bilirubin
B- Hemosiderin
C- Melanin
D- Thromboplastin

B- Hemosiderin- Heme pigment of the blood is transformed into yellowish brown hemosiderin granules which are accumulated at the site of injury resulting in the purple color of the bruise.

 

Question 6. An old patient with a history of a 2-week blunt trauma to his thigh develops an area of yellow-brown color at the site of injury. Which one of the following substances is responsible for this color?

A- Bilirubin
B- Hemosiderin
C- Lipofuscin
D- Melanin

B- Hemosiderin- It is developed from the iron component of hemoglobin released from the destruction of red blood cells at the site of injury.

 

Question 7. A 26-year-old man with a history of HIV infection presents with fatigue and nuchal rigidity for 3 days. Lumber puncture shows increased leukocytes. India ink preparation detects which one of the following organisms?

A- Aspergillus fumigatus
B- Cryptococcus neoformans
C- Streptococcus pneumonia
D- Toxoplasma gondii

B- Cryptococcus neoformans- It is the only one on the list can be seen with India ink preparation.

 

Question 8. Which one of the following cellular pathological changes affects myocardial fibers in a case of irreversible myocardial infarction?

A- Depletion of myoglobin stores
B- Decreased intracellular pH
C- Increased cytoplasmic sodium
D- Karyorrhexis of the nuclei

D- Karyorrhexis of the nuclei- Dissolution of nuclei by karyorrhexis is irreversible. Other choices may occur but they are all reversible.

 

Question 9. An empty scrotal sac is found upon examination of a newborn male. Which of the following is the most likely abnormality?

A- Agenesis
B- Hypogonadism
C- Undescended testis
D- Venous atresia

C- Undescended testis- Incomplete descent is the most common male gonadal abnormality. Other options occur sometimes but UT is the most common condition.

 

Question 10. A young man presents to the ER with a head injury. He lost consciousness after the accident but he is alert now. A CT scan shows convex-shaped area of hemorrhage over the left parietal region. Which of the following structures is the most likely to be injured due to this accident?

A- Cavernous sinus
B- Inferior cerebral artery
C- Middle meningeal artery
D- Superior cerebellar artery

C- Middle meningeal artery- This is a case of epidural hematoma due to damage of middle meningeal artery caused by the accident. It is an emergency and should be treated instantly to avoid death or other complications.

 

Question 11. A young female presents with areas of erythema and itching over the skin of her hands, arms, and legs two hours after she ate nuts. Which of the following immunological reactions is the most likely responsible?

A- Anaphylaxis
B- Cell-mediated hypersensitivity
C- Complement activity
D- Immune complex deposition

A- Anaphylaxis- This is a case of type 1 hypersensitivity which is characterized by IgE, mast cells and histamine release. It can progress to anaphylactic shock. Other immunological reactions are involved with other types of hypersensitivity.

 

Question 12. Release of which of the following chemical mediators results in pain in cases of acute inflammation?

A- Complement C3b
B- Histamine
C- Prostaglandin
D- Serotonin

C- Prostaglandin- Release of prostaglandin and bradykinin is responsible for pain in acute inflammation. Aspirin inhibits cyclooxygenase pathway which decreases prostaglandin synthesis and improves symptoms.

 

Question 13. Chemotherapeutic agents use may result in the loss of individual neoplastic cells through which of the following mechanisms?

A- Acute inflammation
B- Apoptosis
C- Coagulative necrosis
D- Phagocytosis

B- Apoptosis- The effect of chemotherapeutic cells on neoplastic cells, not normal cell, is caused by induction of cell death through apoptosis.

 

Question 14. Which one of the following differentiates exudate from transudate?

A- Few leukocytes
B- Low protein content
C- High specific gravity
D- High osmotic pressure

C- High specific gravity- The key feature that differentiates exudate from transudate is its high protein content and specific gravity. Exudate results from increased capillary permeability (e.g., inflammation, infection, malignancy). It is rich in proteins, has a high specific gravity (>1.020), and often contains many inflammatory cells. Transudate results from increased hydrostatic pressure or decreased oncotic pressure (e.g., heart failure, cirrhosis, nephrotic syndrome). It has low protein content, few or no leukocytes, and low specific gravity (<1.012).

 

Hematopathology

Question 15. A 32-year-old woman presents with fatigue and dark urine. Laboratory studies show anemia, elevated LDH, and decreased haptoglobin. A direct Coombs test is positive. What is the most likely diagnosis?

A- Autoimmune hemolytic anemia
B- Glucose-6-phosphate dehydrogenase deficiency
C- Hereditary spherocytosis
D- Sickle cell disease

A- Autoimmune hemolytic anemia- A positive direct Coombs test indicates antibodies directed against RBCs, causing autoimmune hemolytic anemia with extravascular hemolysis.

 

Question 16. A 58-year-old man presents with fatigue and easy bruising. Peripheral smear shows blasts with Auer rods. Which cytogenetic abnormality is most characteristic of this disease?

A- t(9;22)
B- t(15;17)
C- t(8;14)
D- del(5q)

B- t(15;17)- Acute promyelocytic leukemia is associated with t(15;17), involving the PML-RARα fusion gene, and is treated with all-trans retinoic acid.

 

Question 17. A 42-year-old woman presents with fatigue and glossitis. Peripheral smear shows macrocytosis and hypersegmented neutrophils. Which additional finding is most likely present?

A- Decreased reticulocyte count due to hemolysis
B- Elevated bilirubin due to RBC destruction
C- Increased homocysteine levels
D- Low ferritin levels

C- Increased homocysteine levels- Megaloblastic anemia (B12 or folate deficiency) causes impaired DNA synthesis, leading to macrocytosis and elevated homocysteine.

 

Question 18. A 36-year-old woman presents with fatigue and pallor. Peripheral smear shows microcytic, hypochromic red blood cells with basophilic stippling. She works in a battery factory. What is the most likely diagnosis?

A- Iron deficiency anemia
B- Lead poisoning
C- Sideroblastic anemia
D- Thalassemia

B- Lead poisoning- Lead inhibits heme synthesis and causes basophilic stippling of RBCs, abdominal pain, and neuropathy. Common in battery, paint, or smelting workers.

 

Question 19. A 70-year-old woman presents with severe bone pain and recurrent fractures. Laboratory tests show hypercalcemia, normal PTH, and elevated ALP. Bone biopsy reveals lytic lesions with multinucleated giant cells. Which of the following is the most likely diagnosis?

A- Multiple myeloma
B- Osteoporosis
C- Osteosarcoma
D- Paget disease of bone

A- Multiple myeloma- Multiple myeloma causes osteolytic lesions due to malignant plasma cells producing osteoclast-activating factors. Presents with bone pain, fractures, and hypercalcemia.

 

Question 20. A 65-year-old man presents with progressive shortness of breath and swelling of his legs. Autopsy shows a heart that is firm and rubbery with amyloid deposition between myocardial fibers. Which of the following best describes the staining characteristics of amyloid?

A- Congo red positive, apple-green birefringence under polarized light
B- Periodic acid-Schiff positive, resistant to diastase
C- Oil Red O positive, indicating lipid material
D- Prussian blue positive, indicating iron deposition

A- Congo red positive, apple-green birefringence under polarized light- Amyloid deposits are confirmed by Congo red stain showing apple-green birefringence. It indicates abnormal fibrillar protein deposition.

 

Question 21. A 45-year-old woman presents with fatigue and mild hepatosplenomegaly. Peripheral smear reveals teardrop-shaped red cells (dacrocytes) and nucleated RBCs. Bone marrow biopsy is “dry tap.” What is the most likely diagnosis?

A- Aplastic anemia
B- Myelofibrosis
C- Chronic myeloid leukemia
D- Megaloblastic anemia

B- Myelofibrosis- Bone marrow fibrosis causes extramedullary hematopoiesis and teardrop RBCs. Aspiration yields a “dry tap.”

 

Question 22. A 23-year-old college student presents with fever, sore throat, and lymphadenopathy. Peripheral smear shows atypical lymphocytes with abundant basophilic cytoplasm. Which of the following is the most likely causative agent?

A- Cytomegalovirus
B- Adenovirus
C- Epstein-Barr virus
D- Streptococcus pyogenes

C- Epstein-Barr virus- EBV causes infectious mononucleosis with atypical reactive lymphocytes, positive Monospot test, and posterior cervical lymphadenopathy.

 

Question 23. A 72-year-old man with a 40-pack-year smoking history presents with hematuria and weight loss. CT shows a renal mass. Biopsy reveals polygonal cells with clear cytoplasm. Which paraneoplastic syndrome is most commonly associated with this tumor?

A- Hypercalcemia due to PTHrP secretion
B- Hypoglycemia due to insulin-like factor secretion
C- Polycythemia due to excess erythropoietin
D- SIADH leading to hyponatremia

C- Polycythemia due to excess erythropoietin- Clear cell renal cell carcinoma, often linked with smoking, can produce erythropoietin, leading to paraneoplastic polycythemia. Cells appear with clear cytoplasm due to lipid and glycogen content.

 

Question 24. A 6-year-old boy is diagnosed with glucose-6-phosphate deficiency anemia. Which of the following is the pathogenesis of this condition?

A- Excessive reduction of glutathione
B- Inability to produce enough NADPH
C- Production of huge amount of NADPH

B- Inability to produce enough NADPH- This condition is an X-linked recessive disorder. It is characterized by inability to produce enough NADPH to reduce glutathione. It causes hemolysis to the RBCs when the patient is exposed to oxidative stress. It is common in boys of African and Mediterranean origin.

 

Question 25. Which one of the following conditions is characterized by hemolytic episodes caused by increased erythrocyte sensitivity to complement lytic actions?

A- Glucose-6-phosphate dehydrogenase deficiency anemia
B- Hereditary spherocytosis
C- Paroxysmal nocturnal hemoglobinuria
D- Sickle cell anemia

C- Paroxysmal nocturnal hemoglobinuria- A- Is caused by enzyme deficiency. B- Is caused by autosomal dominant disorder. D- Is caused by nucleotide change.

 

Question 26. A patient presents with multiple ecchymoses of the skin, high prothrombin and partial thromboplastin times, Low serum He, low platelet count and positive D-Dimer test. Which of the following is the most likely diagnosis?

A- Disseminated intravascular coagulopathy
B- Hemophilia A
C- Vitamin K deficiency
D- von Willebrand disease

A- Disseminated intravascular coagulopathy- D-Dimer test is positive is diagnostic and it caused by fibrin degradation products which result in widespread clotting.

 

Question 27. Which of the following are the major sites for heme synthesis?

A- Bone marrow and kidney
B- Bone marrow and liver
C- Bone marrow and spleen
D- Kidney and liver
E- Kidney and spleen

B- Bone marrow and liver- The bone marrow is responsible for producing heme for hemoglobin synthesis in red blood cells, while the liver synthesizes heme for various other heme-containing proteins, such as cytochromes involved in electron transport and enzymes like catalase and cytochrome P450.

 

Question 28. Which one of the following procoagulant factors is NOT produced by endothelial cells?

A- Fibrinogen
B- Prostacyclin
C- Thromboxane A2
D- von Willebrand’s factor (vWF)

A- Fibrinogen- Fibrinogen is not produced by endothelial cells. It is primarily synthesized by hepatocytes in the liver. It plays a crucial role in blood clotting by being converted into fibrin, which forms the structural basis of a blood clot. Prostacyclin is primarily synthesized by endothelial cells and acts as an inhibitor of platelet aggregation and a vasodilator. Thromboxane A2 is produced by activated platelets and endothelial cells. It promotes platelet aggregation and vasoconstriction. von Willebrand’s factor (vWF) is produced by endothelial cells, specifically endothelial cells lining blood vessels and by megakaryocytes in bone marrow. It plays a crucial role in hemostasis by mediating the adhesion of platelets to damaged blood vessel walls.

 

Cardiovascular and Pulmonary Pathology

Question 29. A 70-year-old man presents with hemoptysis and weight loss. Lung biopsy reveals malignant cells that stain positive for neuroendocrine markers and show nuclear molding. What is the most likely diagnosis?

A- Adenocarcinoma
B- Large cell carcinoma
C- Small cell carcinoma
D- Squamous cell carcinoma

C- Small cell carcinoma- Small cell carcinoma is a neuroendocrine tumor associated with smoking, nuclear molding, and paraneoplastic syndromes.

 

Question 30. A 52-year-old man presents with chronic cough, hemoptysis, and digital clubbing. Chest X-ray reveals a coin lesion in the lung. Biopsy shows malignant glandular structures producing mucin. What is the most likely diagnosis?

A- Adenocarcinoma
B- Large cell carcinoma
C- Small cell carcinoma
D- Squamous cell carcinoma

A- Adenocarcinoma- Adenocarcinoma is the most common lung cancer in both smokers and nonsmokers. It tends to be peripheral and shows mucin-producing glandular cells.

 

Question 31. A 22-year-old man presents with a sudden onset of severe chest pain. Imaging reveals a spontaneous pneumothorax. Lung biopsy shows rupture of small subpleural blebs. Which condition is most commonly associated?

A-Asthma
B-Chronic smoking history
C-Pulmonary fibrosis
D-Tall, thin body habitus

D-Tall, thin body habitus- Primary spontaneous pneumothorax is most common in tall, thin young men due to rupture of apical blebs.

 

Question 32. A 50-year-old man presents with chronic cough and weight loss. A chest X-ray reveals a cavitary lesion in the upper lobe. Biopsy shows caseating granulomas with acid-fast bacilli. Which organism is responsible for this pathology?

A- Aspergillus fumigatus
B- Mycobacterium tuberculosis
C- Histoplasma capsulatum
D- Klebsiella pneumoniae

B- Mycobacterium tuberculosis- TB classically produces caseating granulomas, especially in the upper lobes. Acid-fast bacilli on Ziehl-Neelsen stain confirm the diagnosis.

 

Question 33. A 65-year-old man presents with progressive dyspnea and a nonproductive cough. Chest X-ray reveals bilateral reticular opacities. Lung biopsy shows honeycomb fibrosis. Which of the following is the most likely diagnosis?

A- Chronic bronchitis
B- Hypersensitivity pneumonitis
C- Idiopathic pulmonary fibrosis
D- Sarcoidosis

C- Idiopathic pulmonary fibrosis- Idiopathic pulmonary fibrosis is characterized by progressive scarring of lung tissue, leading to honeycomb fibrosis. Chronic bronchitis shows mucus hypersecretion, hypersensitivity pneumonitis is immune-mediated with granulomatous inflammation, and sarcoidosis has noncaseating granulomas.

 

Question 34. Which one of the following is the most frequent form of pericarditis associated with myocardial infarction?

A- Constrictive pericarditis
B- Fibrinous pericarditis
C- Hemorrhagic pericarditis
D- Purulent pericarditis

B- Fibrinous pericarditis- It is the most common pericarditis associated with MI. It occurs within the first few days after a transmural MI due to inflammation extending to the pericardial surface. It presents with sharp chest pain, worse with inspiration or lying flat, and may be accompanied by a pericardial friction rub on auscultation.

 

Question 35. Which of the following is the most frequent form of pericarditis associated with myocardial infarction?

A- Fibrinous pericarditis
B- Hemorrhagic pericarditis
C- Serous pericarditis
D- Suppurative pericarditis

C-Serous pericarditis- Myocardial infarction can lead to inflammation of the pericardium, and serous pericarditis is characterized by an accumulation of serous fluid in the pericardial sac. Fibrinous pericarditis and hemorrhagic pericarditis can also occur but are less common. Suppurative pericarditis is characterized by a purulent or pus-like exudate. It is rare and typically associated with bacterial infections.

 

Question 36. Which one of the following lung conditions occurs mostly in sandblasters and is characterized by fibrotic nodules in the upper lobes of the lung?

A- Asbestosis
B- Berylliosis
C- Coal Workers’ Pneumoconiosis
D- Silicosis

D- Silicosis- It is caused by inhalation of silica and is common in sandblasters and silica miners. These patients have increased risk for TB.

 

Question 37. Which one of the following parts of the heart is the major consumer of oxygen and requires the best blood supply?

A- Left atrium
B- Left ventricle
C- Right atrium
D- Right ventricle

B- Left ventricle- It is the major site of myocardial infarction as it needs the highest amount of oxygen and nutrients.

 

Question 38. Which one of the following conditions is most likely affects the lungs of a patient with Parkinsonism?

A- Atherosclerosis
B- Arteriosclerosis
C- Embolism
D- Thrombosis

C- Embolism- It is the most common condition due to frequent immobilization of patients with Parkinsonism. Other conditions are rare in general.

 

Question 39. Which of the following features are most likely seen in a case of Takayasu arteritis?

A- Blanching and cyanosis of the fingers and toes
B- Blindness and pulseless upper extremities
C- Febrile lymphadenopathy with rash
D- Major organ failures

B- Blindness and pulseless upper extremities-A- Is Raynaud disease. C- Is Kawasaki disease. D- Is polyarteritis nodosa and some autoimmune diseases.

 

Question 40. A middle-aged woman presents with stabbing chest pain that radiates to the back. She has a history of Marfan syndrome and poorly controlled hypertension. Which of the following is the most likely diagnosis?

A- Aortic dissection
B- Hypertrophic cardiomyopathy
C- Myocardial infarction
D- Pericarditis

A- Aortic dissection- It is very common with Marfan syndrome due to a tear in aortic intima results from cystic medial necrosis.

 

Question 41. Which of the following locations is the most common site of mural thrombus following myocardial infarction?

A- Aorta
B- Left ventricle
C- Right atrium
D- Right ventricle

B- Left ventricle- It is the major user of oxygen which requires a good blood supply. Damage to left ventricle through ischemic heart disease causes mural thrombus.

 

Question 42. Which of the following are the primary vessels responsible for the regulation of blood pressure?

A- Arteries
B- Arterioles
C- Capillaries
D- Veins
E- Venuses

B- Arterioles- Arterioles are the small branches of arteries that lead directly into capillary beds. They have muscular walls that can constrict or dilate to regulate blood flow and systemic vascular resistance. Because of this, they play the primary role in controlling blood pressure and directing blood to specific tissues as needed. Arteries mainly serve as conduits for blood flow. Capillaries are for the exchange of gases and nutrients. Veins serve as blood reservoirs and return blood to the heart. “Venuses” is not a correct anatomical term.

 

GI, Liver and Pancreas Pathology

Question 43. A 45-year-old man presents with epigastric pain that improves with eating. Endoscopy reveals a duodenal ulcer. Which organism is most commonly responsible for this condition?

A- Campylobacter jejuni
B- Clostridioides difficile
C- Helicobacter pylori
D- Vibrio cholerae

C- Helicobacter pylori- H. pylori infection causes chronic gastritis and increases risk for duodenal ulcers, gastric adenocarcinoma, and MALT lymphoma.

 

Question 44. A 34-year-old woman presents with chronic diarrhea and abdominal pain. Colonoscopy reveals transmural inflammation with skip lesions. Which complication is most likely in this condition?

A- Toxic megacolon
B- Colorectal adenocarcinoma
C- Fistula formation
D- Primary sclerosing cholangitis

C- Fistula formation- Crohn disease causes transmural inflammation, predisposing to fistulas, strictures, and abscesses.

 

Question 45. A 61-year-old man presents with progressive jaundice, weight loss, and pruritus. Imaging reveals dilation of the bile ducts and a mass near the hepatic hilum. Which tumor is most likely responsible for this finding?

A- Hepatocellular carcinoma
B- Cholangiocarcinoma
C- Gallbladder adenocarcinoma
D- Pancreatic neuroendocrine tumor

B- Cholangiocarcinoma- Cholangiocarcinoma arises from bile duct epithelium and can obstruct bile flow, leading to jaundice and pruritus. Risk factors include primary sclerosing cholangitis and chronic biliary inflammation.

 

Question 46. A 59-year-old man presents with progressive dysphagia. Endoscopy reveals an ulcerated mass in the distal esophagus. Biopsy shows malignant gland-forming cells. Which risk factor is most strongly associated with this condition?

A- Alcohol consumption
B- Chronic gastroesophageal reflux disease
C- Human papillomavirus infection
D- Iron deficiency anemia

B- Chronic gastroesophageal reflux disease- Esophageal adenocarcinoma arises from Barrett’s esophagus, which develops due to long-standing GERD.

 

Question 47. A 67-year-old man presents with sudden abdominal pain and bloody diarrhea. CT scan shows thickening of the colon at the splenic flexure. Which vascular pathology best explains this finding?

A-Ischemic colitis due to watershed infarction
B-Mesenteric venous congestion
C-Portal vein thrombosis
D-Ulcerative colitis

B-Ischemic colitis due to watershed infarction- The splenic flexure is a watershed area between SMA and IMA territories, making it vulnerable to ischemia during hypoperfusion.

 

Question 48. A 55-year-old man with chronic alcoholism presents with ascites and spider angiomas. Liver biopsy shows regenerative nodules surrounded by fibrous septa. What is the underlying pathological process?

A-Acute hepatitis
B-Cirrhosis
C-Fatty liver disease
D-Hepatocellular carcinoma

B-Cirrhosis- Cirrhosis is characterized by diffuse fibrosis and regenerative nodules, leading to portal hypertension and liver dysfunction.

 

Question 49. A 30-year-old woman presents with chronic diarrhea and weight loss. Biopsy of the small intestine shows blunted villi and increased intraepithelial lymphocytes. Symptoms improve when she avoids wheat. What is the most likely diagnosis?

A- Celiac disease
B- Irritable bowel syndrome
C- Tropical sprue
D- Whipple disease

A- Celiac disease- Celiac disease is an autoimmune reaction to gluten causing villous atrophy, lymphocytic infiltration, and malabsorption, with improvement after removing gluten.

 

Question 50. A 29-year-old woman presents with severe abdominal pain and hypotension following a ruptured ectopic pregnancy. Autopsy of the fallopian tube shows large cytoplasmic vacuoles in hepatocytes. What is the most likely cause of this hepatic change?

A- Amyloidosis
B- Apoptosis
C- Fatty change due to hypoxia
D- Hydropic degeneration

C- Fatty change due to hypoxia- Shock leads to hepatic hypoxia, causing reversible fatty change (steatosis) in hepatocytes due to impaired lipid metabolism.

 

Question 51. A 48-year-old man presents with jaundice, dark urine, and pale stools. Lab tests show elevated direct bilirubin and markedly elevated alkaline phosphatase. Ultrasound reveals dilation of intrahepatic bile ducts. What is the most likely cause?

A-Gilbert disease
B-Hemolytic anemia
C-Obstruction of the common bile duct
D-Viral hepatitis

C-Obstruction of the common bile duct- Post-hepatic (obstructive) jaundice causes elevated direct bilirubin, pale stools, dark urine, and high ALP due to blocked bile flow.

 

Question 52. A 60-year-old woman presents with progressive jaundice and weight loss. Imaging shows a mass at the head of the pancreas. Which of the following is the most likely paraneoplastic finding?

A- Cushing syndrome
B- Hypercalcemia due to PTHrP secretion
C- Hyponatremia due to SIADH
D- Migratory thrombophlebitis (Trousseau syndrome)

D- Migratory thrombophlebitis (Trousseau syndrome)- Pancreatic adenocarcinoma is strongly associated with Trousseau syndrome (recurrent venous thrombosis at different sites).

 

Question 53. A 62-year-old man with a history of chronic alcohol use presents with weight loss, epigastric pain, and jaundice. CT scan shows a mass in the head of pancreas. Which tumor marker is most useful for this diagnosis?

A- Alpha-fetoprotein (AFP)
B- Cancer antigen 19-9 (CA 19-9)
C- Carcinoembryonic antigen (CEA)
D- Prostate-specific antigen (PSA)

B- Cancer antigen 19-9 (CA 19-9)- CA 19-9 is the most widely used tumor marker for pancreatic cancer. AFP is for hepatocellular carcinoma, PSA for prostate cancer, and CEA is less specific (colorectal, pancreatic, and gastric cancers).

 

Question 54. A 58-year-old man presented with abdominal pain and jaundice. Lab results show elevated conjugated bilirubin and alkaline phosphatase. A liver biopsy shows proliferation of bile ducts, fibrosis, and “onion-skin” appearance. Which of the following is the most likely diagnosis?

A- Alcoholic cirrhosis
B- Autoimmune hepatitis
C- Primary biliary cholangitis
D- Primary sclerosing cholangitis

D- Primary sclerosing cholangitis- Primary sclerosing cholangitis (PSC) is characterized by bile duct fibrosis and “onion-skin” appearance. It is strongly associated with ulcerative colitis and p-ANCA positivity.

 

Question 55. A 55-year-old man with a long history of alcohol use presents with abdominal distension. Physical exam reveals shifting dullness and spider angiomas on the chest. His lab results are: total bilirubin 3.2 mg/dL, albumin 2.1 g/dL, and an INR of 1.9. Which of the following best explains the pathophysiology of his condition?

A- Autoimmune destruction of intrahepatic bile ducts
B- Deposition of α1-antitrypsin polymers in hepatocytes
C- Fibrosis and nodular regeneration disturbing hepatic architecture
D- Viral cytotoxicity with hepatocyte necrosis

C- Fibrosis and nodular regeneration disturbing hepatic architecture- Chronic alcohol use leads to cirrhosis, characterized by fibrosis and regenerative nodules that distort hepatic blood flow and function, resulting in portal hypertension and synthetic dysfunction.

 

Question 56. A patient presents with fever, jaundice, abdominal pain, hepatomegaly and ascites. Microscopic examination of liver shows cellular swelling, necrosis, neutrophilic infiltration around the cells and sinusoidal and perivenular fibrosis. Which of the following is the most likely diagnosis?

A- Acetaminophen toxicity
B- Alcoholic hepatitis
C- Budd-Chiari syndrome
D- pyogenic liver abscess

B- Alcoholic hepatitis- Clinical picture and microscopic examination are consistent with alcoholic hepatitis. Acetaminophen toxicity may cause liver damage, but it is different form of cellular pathology and does not usually present with ascites. Budd-Chiari syndrome is characterized by liver congestion but does not usually cause fever, jaundice or cellular changes. Pyogenic liver abscess does not usually cause hepatomegaly, ascites or jaundice.

 

Question 57. In a case of esophageal dysphagia, which one of the following is considered a mechanical obstruction versus a motility disorder?

A- Achalasia
B- Chagas disease
C- Diffuse esophageal spasm
D- Extrinsic compression

D- Extrinsic compression- caused by different abnormalities such as enlarged left atrium, aortic aneurysm or aberrant subclavian artery. Other choices are motility disorders.

 

Question 58. A child presents with low body weight, edema of lower extremities, enlarged abdomen with ascites, and desquamating skin and areas of depigmentation and hyperpigmentation. Which of the following is the most likely diagnosis?

A- Kwashiorkor
B- Marasmus
C- Pellagra
D- Scurvy

A- Kwashiorkor- Hypoalbuminemia and fatty liver are characteristic of kwashiorkor. Young children are the most affected group because of malnutrition and the need for more protein during development.

 

Question 59. Which of the following locations is the most common site of gastrinoma?

A- Ileum
B- Liver
C- Pancreas
D- Stomach

C- Pancreas- Zollinger-Ellison syndrome is a rare condition caused by gastrinoma of the pancreas and results in recurrent peptic ulcers within the duodenum and jejunum.

 

Question 60. In which one of the following parts of the GIT most of the ingested iron is absorbed?

A- Stomach
B- Duodenum
C- Ileum
D- Ascending colon
E- Descending colon

B- Duodenum- The acidic environment of the stomach helps to solubilize iron from food, and then in the duodenum, iron absorption occurs primarily through active transport mechanisms.

 

Renal and Urinary Pathology

Question 61. A 70-year-old man presents with progressive difficulty initiating urination and a weak urinary stream. Biopsy reveals nodular enlargement of the periurethral prostate glands. What is the most likely diagnosis?

A- Benign prostatic hyperplasia
B- Prostate adenocarcinoma
C- Prostatic intraepithelial neoplasia
D- Prostatitis

A- Benign prostatic hyperplasia- BPH results from androgen-driven hyperplasia of periurethral glands, causing urinary obstruction in older men.

 

Question 62. A 64-year-old man with a long history of smoking presents with hematuria. Cystoscopy reveals a papillary tumor arising from the bladder mucosa. Which molecular alteration is most commonly associated with low-grade papillary urothelial carcinoma?

A- KRAS mutation
B- FGFR3 mutation
C- BRAF mutation
D- APC mutation

B- FGFR3 mutation- Low-grade papillary urothelial carcinomas are commonly associated with FGFR3 mutations, leading to uncontrolled cell proliferation.

 

Question 63. A 63-year-old man with long-standing diabetes presents with progressive renal failure. Renal biopsy shows nodular glomerulosclerosis with Kimmelstiel–Wilson nodules. What is the most likely diagnosis?

A- Amyloidosis
B- Diabetic nephropathy
C- Focal segmental glomerulosclerosis
D- Membranoproliferative glomerulonephritis

B- Diabetic nephropathy- Diabetic nephropathy is characterized by mesangial expansion and Kimmelstiel–Wilson nodules due to chronic hyperglycemia.

 

Question 64. A 35-year-old man presents with hematuria and rapidly worsening renal function. Renal biopsy shows crescent formation in glomeruli. Which mechanism best explains this pathology?

A- Basement membrane thickening
B- Immune complex deposition
C- Podocyte injury
D- Proliferation of parietal epithelial cells

D- Proliferation of parietal epithelial cells- Crescentic (rapidly progressive) glomerulonephritis is characterized by crescents formed from proliferating parietal epithelial cells and macrophages.

 

Question 65. A 27-year-old man develops acute renal failure after a sore throat 2 weeks ago. Urinalysis shows hematuria with red blood cell casts. Light microscopy of a kidney biopsy reveals hypercellular glomeruli. Which of the following is the most likely diagnosis?

A- Membranous nephropathy
B- Minimal change disease
C- Post-streptococcal glomerulonephritis
D- Rapidly progressive glomerulonephritis

C- Post-streptococcal glomerulonephritis- This condition follows group A streptococcal infection. It presents with hematuria, edema, hypertension, and RBC casts. Biopsy shows hypercellular glomeruli due to immune complex deposition.

 

Question 66. A 55-year-old man presents with hematuria. Cystoscopy shows a papillary growth in the bladder. Histology reveals malignant transitional cells. Which of the following is the most significant risk factor for this condition?

A- Chronic cystitis
B- Cigarette smoking
C- Cyclophosphamide therapy
D- Schistosoma haematobium infection

B- Cigarette smoking- Transitional cell carcinoma (urothelial carcinoma) is strongly linked to cigarette smoking, which increases exposure to carcinogens excreted in urine. Schistosoma infection predisposes to squamous cell carcinoma of the bladder, not transitional.

 

Question 67. A 6-year-old boy presents with generalized edema and frothy urine. Lab results: urine protein 4+, serum albumin 1.8 g/dL, and elevated cholesterol. A renal biopsy shows normal glomeruli on light microscopy, but electron microscopy reveals effacement of podocyte foot processes. What is the most likely diagnosis?

A- Focal segmental glomerulosclerosis
B- Membranous nephropathy
C- Minimal change disease
D- Post-streptococcal glomerulonephritis

C- Minimal change disease- Minimal change disease is the most common cause of nephrotic syndrome in children, with podocyte foot process effacement seen on electron microscopy and normal light microscopy. It responds dramatically to corticosteroids.

 

Question 68. Which one of the following conditions is characterized by high blood pressure, hypokalemia and elevated renal potassium?

A- Fanconi syndrome
B- Liddle syndrome
C- Tay-Sachs disease
D- Waardenburg syndrome

B- Liddle syndrome- It is a hereditary disease occurs early in life and known by severe hypertension in an early age.

 

Question 69. Which one of the following factors stimulates the renal secretion of renin?

A- Decreased pressure in the afferent glomerular arterioles
B- Increased pressure in the afferent glomerular arterioles
C- Increased serum sodium ion concentration
D- Increased chloride ion concentration in the renal distal tubules

A- Decreased pressure in the afferent glomerular arterioles- Renin is secreted by the juxtaglomerular (JG) cells of the kidney when there is a drop in renal perfusion pressure. These specialized cells act as intrarenal baroreceptors that detect reduced stretch in the afferent arteriole, leading to increased renin release. Renin secretion is also stimulated by: Decreased sodium chloride concentration at the macula densa (not increased). Sympathetic stimulation via β₁-adrenergic receptors.

 

Endocrine, Breast and Reproductive Pathology

Question 70. A 58-year-old woman with obesity and type 2 diabetes presents with abnormal uterine bleeding. Endometrial biopsy reveals atypical glandular proliferation. Which malignancy is she at greatest risk of developing?

A- Cervical squamous carcinoma
B- Endometrial carcinoma
C- Ovarian serous carcinoma
D- Vaginal carcinoma

B- Endometrial carcinoma- Unopposed estrogen exposure (obesity, diabetes, PCOS) increases risk of endometrial hyperplasia progressing to endometrial carcinoma.

 

Question 71. A 27-year-old woman presents with a painless thyroid nodule. Biopsy shows tumor cells forming follicles but without the nuclear features of papillary carcinoma. Capsular invasion is present. What is the most likely diagnosis?

A- Anaplastic thyroid carcinoma
B- Follicular thyroid carcinoma
C- Medullary thyroid carcinoma
D- Papillary thyroid carcinoma

B- Follicular thyroid carcinoma- Follicular carcinoma is diagnosed by capsular or vascular invasion and lacks the nuclear features seen in papillary carcinoma.

 

Question 72. A 50-year-old man presents with progressive muscle weakness and fatigue. Imaging reveals a mediastinal mass. Which autoimmune disease is most commonly associated with this tumor?

A- Multiple sclerosis
B- Myasthenia gravis
C- Rheumatoid arthritis
D- Systemic lupus erythematosus

B- Myasthenia gravis- Thymomas are frequently associated with myasthenia gravis due to autoantibodies against acetylcholine receptors.

 

Question 73. A 45-year-old woman presents with episodic headaches, sweating, and palpitations. Imaging reveals an adrenal medullary tumor. Which histologic pattern is most characteristic of this tumor?

A- Keratin pearls
B- Psammoma bodies
C- Sheets of small blue cells
D- Zellballen pattern

D- Zellballen pattern- Pheochromocytomas show nests (zellballen) of chromaffin cells surrounded by sustentacular cells.

 

Question 74. A 24-year-old woman presents with neck swelling. Fine-needle aspiration of a thyroid nodule shows polygonal cells with amyloid deposits in the stroma. Which hormone is most likely elevated in this patient?

A-Calcitonin
B-Parathyroid hormone
C-Thyroxine (T4)
D-Triiodothyronine (T3)

A-Calcitonin- Medullary carcinoma of the thyroid arises from parafollicular C cells and produces calcitonin. Amyloid deposition is due to calcitonin accumulation.

 

Question 75. A 40-year-old woman presents with a painless breast lump. Biopsy reveals malignant cells forming duct-like structures confined within the basement membrane. Which of the following is the most likely diagnosis?

A- Ductal carcinoma in situ (DCIS)
B- Fibroadenoma
C- Invasive ductal carcinoma
D- Lobular carcinoma in situ (LCIS)

A- Ductal carcinoma in situ (DCIS)- DCIS is a non-invasive breast carcinoma confined to ducts without basement membrane invasion. Invasive ductal carcinoma shows invasion into the surrounding stroma.

 

Question 76. A 45-year-old woman presents with painless swelling in her neck. Fine needle aspiration cytology shows “Orphan Annie-eye nuclei” and psammoma bodies. Which of the following is the most likely diagnosis?

A- Anaplastic carcinoma of thyroid
B- Follicular carcinoma of thyroid
C- Medullary carcinoma of thyroid
D- Papillary carcinoma of thyroid

D-Papillary carcinoma of thyroid- Papillary thyroid carcinoma is the most common thyroid cancer. Classic features include clear nuclei with central clearing, “Orphan Annie-eye nuclei”, and calcified concentric structures, “Psammoma bodies”.

 

Question 77. Which one of the following laboratory tests can differentiate primary aldosteronism from secondary aldosteronism?

A- Plasma aldosterone concentration
B- Plasma renin activity
C- Serum cortisol
D- Serum sodium

B- Plasma renin activity- Measuring plasma renin activity and calculating the aldosterone-to-renin ratio (ARR) is the best approach to distinguish between primary and secondary aldosteronism. In primary aldosteronism, renin is suppressed due to feedback inhibition while ARR is high. In secondary aldosteronism, renin is increased while ARR is normal or low.

 

Question 78. Which of the following conditions is characterized by hypertension due to sodium retention, hypokalemia, and decreased renin secretion?

A- Conn syndrome
B- Cushing syndrome
C- Diabetes insipidus
D- Renal ischemia

A- Conn syndrome- It is a primary aldosteronism leads to increased sodium and water retention resulting in hypertension. Hypertension is causing decreased renin secretion due to its negative feedback. Renal ischemia is causing increased renin secretion, not decreased.

 

Question 79. Which of the following is the most common cause of death in an old patient with uncontrolled diabetes?

A- Cerebral hemorrhage
B- Hyperosmolar coma
C- Myocardial infarction
D- Pulmonary embolism

C- Myocardial infarction- Advanced coronary atherosclerosis leading to MI is the most common cause event in diabetic patients.

 

Question 80. A 29-year-old woman presents with bloody discharge from her right breast for 3 weeks. There is no pain, fever or swellings. There is no breast mass or lymphadenopathy. Which of the following is the most likely diagnosis?

A- Intraductal papilloma
B- Metastatic carcinoma
C- Pregnancy
D- Prolactinoma

A- Intraductal papilloma- These are localized in the lactiferous tubules behind the nipple and bleeding is the only sign.

 

Question 81. Control of diabetes is most likely determined by which one of the following laboratory tests?

A- Fasting blood glucose
B- Hemoglobin A1C
C- Random blood glucose
D- Urinary glucose content

B- Hemoglobin A1C- Diagnosis of DM can be made by testing fasting, random and urinary blood glucose but control of diabetes is best evaluated by measurement of HbA1C.

 

Question 82. Which of the following predicts a better prognosis in cases of breast cancer?

A- Family history of breast cancer
B- No metastases in the nearest lymph nodes
C- Positive estrogen receptor
D- Tumor stage 2

B- No metastases in the nearest lymph nodes- low stage breast cancer is successfully treatable.

 

Musculoskeletal, Skin and Nervous System Pathology

Question 83. A 14-year-old boy presents with a rapidly enlarging, painful mass around the distal femur. X-ray shows a destructive bone lesion with a “sunburst” periosteal reaction. What is the most likely diagnosis?

A- Chondrosarcoma
B- Ewing sarcoma
C- Osteochondroma
D- Osteosarcoma

D- Osteosarcoma- Osteosarcoma is the most common primary malignant bone tumor in adolescents. Radiographs often show a sunburst pattern and Codman triangle.

 

Question 84. A 65-year-old woman presents with progressive back pain. X-ray shows vertebral compression fractures. Bone biopsy reveals reduced bone mass with normal mineralization. What is the most likely diagnosis?

A- Osteoporosis
B- Osteomalacia
C- Hyperparathyroidism
D- Paget’s disease

A- Osteoporosis- Osteoporosis involves decreased bone mass with normal mineralization, leading to fragility fractures, especially in vertebrae and hips.

 

Question 85. A 66-year-old woman presents with bone pain and hearing loss. Laboratory studies show elevated alkaline phosphatase with normal calcium and phosphate levels. What is the most likely underlying pathology?

A- Osteomalacia
B- Osteoporosis
C- Paget’s disease of bone
D- Primary hyperparathyroidism

C- Paget’s disease of bone- Paget disease involves increased and disorganized bone remodeling, causing bone pain, deformities, and elevated ALP with normal calcium levels.

 

Question 86. A 70-year-old man presents with memory loss and personality changes. Autopsy of the brain reveals extracellular beta-amyloid plaques and intracellular neurofibrillary tangles. What protein makes up the neurofibrillary tangles?

A- Alpha-synuclein
B- Beta-amyloid
C- Prion protein
D- Tau protein

D- Tau protein- Neurofibrillary tangles in Alzheimer’s disease consist of hyperphosphorylated tau protein, while plaques are composed of beta-amyloid

 

Question 87. A 55-year-old woman presents with multiple café-au-lait spots and soft, pedunculated skin tumors. Which genetic defect is associated with this condition?

A- Deletion of chromosome 22q
B- Mutation of the RB tumor suppressor gene
C- Mutation of the NF1 tumor suppressor gene
D- Trinucleotide repeat expansion on chromosome 4

C- Mutation of the NF1 tumor suppressor gene- Neurofibromatosis type 1 presents with café-au-lait spots and neurofibromas due to NF1 gene mutation on chromosome 17.

 

Question 88. A 70-year-old man presents with worsening bone pain. His alkaline phosphatase is markedly elevated, but calcium and phosphate levels are normal. X-ray shows thickened cortical bone with a mosaic pattern. What is the most likely diagnosis?

A-Hyperparathyroidism
B-Osteomalacia
C-Osteoporosis
D-Paget disease of bone

D-Paget disease of bone- Paget disease causes disorganized bone remodeling, elevated ALP, normal Ca/Pi, and mosaic (jigsaw) bone pattern.

 

Question 89. Which of the following dermal conditions is a blistering disease that develops in individuals allergic to gliadin, a gluten component?

A- Bullous pemphigoid
B- Dermatitis herpetiformis
C- Erythema multiforme
D- Pemphigus vulgaris

B- Dermatitis herpetiformis- It is a chronic blistering skin condition associated with celiac disease, which is caused by an immune reaction to gliadin, a component of gluten. It presents as intensely pruritic papules and vesicles, commonly on the extensor surfaces (elbows, knees, buttocks, back).

 

Question 90. Which one of the following skin pathological conditions is caused by autoantibodies that react with desmosomes or hemidesmosomes leading to disruption of intracellular junctions?

A- Acne vulgaris
B- Bullous pemphigoid
C- Dermatitis herpetiformis
D- Urticaria

B- Bullous pemphigoid- It is considered type II hypersensitivity along with pemphigus vulgaris.

 

Question 91. An elderly woman complains of sharp pain in her right hip region after she falls out of bed. Radiological studies show fractures of the right femoral head and a compressed fracture of T10. Which of the following is the most likely predisposing to these fractures?

A- Acute osteomyelitis
B- Metastases
C- Osteomalacia
D- Osteoporosis

D- Osteoporosis- It is the most common predisposing factor of fractures in the elderly.

 

Question 92. A 79-year-old woman presents with back pain for 3 months. Radiology of the spines shows compression of T11 and T12 vertebrae. There is no other lesion detected. Which of the following is the most likely diagnosis?

A- Ewing sarcoma
B- Metastatic adenocarcinoma
C- Osteoporosis
D- Osteosarcoma

C- Osteoporosis- It is common in old age and leads to compression fractures of vertebrae.

 

Question 93. Which of the following conditions is characterized by irregular blotchy patches of hyperpigmentation localized mostly on the face caused by sun exposure, pregnancy and contraceptive pills?

A- Benign lentigo
B- Freckles
C- Melasma
D- Vitiligo

C- Melasma- This is a typical presentation. A- Lentigo a small oval light brown macule. B- Freckles are light brown macules on the face, shoulders, and trunk. D- Vitiligo is an irregular depigmented skin patch and can occur anywhere.

 

Question 94. Which one of the following conditions is characterized by joint space narrowing and osteophyte formation while bone density appears normal?

A- Gout
B- Osteoarthritis
C- Pseudogout
D- Rheumatoid arthritis

B- Osteoarthritis- The most common arthritis in the elderly population. It affects almost every person at the age of 65 and older to some extent.

 

Question 95. An old man complains of progressive back pain and joint pain for 10 years. There is enlargement in the distal interphalangeal joints, osteophytes on the vertebral bodies, and sclerosis with narrowing of multiple joint spaces. Which of the following is the most likely diagnosis?

A- Gout
B- Osteoarthritis
C- Osteomyelitis
D- Rheumatoid arthritis

B- Osteoarthritis- It is a common progressive condition in old age. It shows erosion and joint space narrowing with osteophytes.

 

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