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FMGE practice questions

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Question 1Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A medical student is asked to identify the nerve injured in a midshaft humerus fracture that causes wrist drop. Which nerve is most commonly involved?

  1. Median nerve
  2. Ulnar nerve
  3. Radial nerve Correct answer.
  4. Musculocutaneous nerve

Explanation

The radial nerve runs in the spiral groove against the posterior humerus, so midshaft fractures commonly injure it. It supplies the wrist and finger extensors, so injury produces wrist drop with sensory loss over the dorsum of the hand.

Question 2Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

During a clinical examination, a patient is found to have loss of pain and temperature sensation over the contralateral body below the lesion with preservation of fine touch. Which spinal cord tract is affected?

  1. Dorsal spinocerebellar tract
  2. Spinothalamic tract Correct answer.
  3. Dorsal columns
  4. Corticospinal tract

Explanation

The spinothalamic tract carries pain and temperature fibres that decussate near their entry level and ascend contralaterally. A lesion therefore causes loss of pain and temperature on the opposite side below the lesion, while dorsal column modalities remain intact.

Question 3Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A newborn presents with a high-pitched cry, feeding difficulty and a musty odour. Deficiency of which enzyme is most likely responsible?

  1. Cystathionine beta-synthase
  2. Homogentisate oxidase
  3. Branched-chain alpha-ketoacid dehydrogenase
  4. Phenylalanine hydroxylase Correct answer.

Explanation

The combination of musty odour, poor feeding and neurological features in a newborn suggests phenylketonuria, caused by deficiency of phenylalanine hydroxylase. Phenylalanine accumulates and is transaminated to phenylketones, producing the characteristic odour.

Question 4Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which of the following best describes the primary function of the sinoatrial node?

  1. It conducts impulses from the atria to the ventricles.
  2. It increases ventricular contractility via sympathetic fibres.
  3. It acts as the natural pacemaker by generating spontaneous depolarisation. Correct answer.
  4. It delays the impulse to allow ventricular filling.

Explanation

The sinoatrial node has the highest rate of spontaneous phase-4 depolarisation and therefore sets the rhythm of the heart. Its cells generate impulses without external stimulation, functioning as the natural pacemaker.

Question 5Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with chronic renal failure develops anaemia that does not respond to iron therapy. Which renal hormone is most likely deficient?

  1. Calcitriol
  2. Erythropoietin Correct answer.
  3. Renin
  4. Aldosterone

Explanation

Erythropoietin is produced mainly by peritubular interstitial cells of the kidney and stimulates erythroid progenitor proliferation. In chronic renal failure its production falls, causing normocytic normochromic anaemia unresponsive to iron alone.

Question 6Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which vitamin deficiency classically produces night blindness due to impaired rhodopsin synthesis?

  1. Vitamin A Correct answer.
  2. Vitamin D
  3. Vitamin C
  4. Vitamin K

Explanation

11-cis-retinal, derived from vitamin A, is the chromophore of rhodopsin in rod cells. Deficiency reduces rhodopsin regeneration and impairs dim-light vision, producing night blindness.

Question 7Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

During glycolysis, which reaction generates ATP by substrate-level phosphorylation at the level of phosphoenolpyruvate?

  1. Conversion of 3-phosphoglycerate to 2-phosphoglycerate
  2. Conversion of phosphoenolpyruvate to pyruvate Correct answer.
  3. Conversion of glucose to glucose-6-phosphate
  4. Conversion of fructose-6-phosphate to fructose-1,6-bisphosphate

Explanation

Pyruvate kinase transfers the phosphate of phosphoenolpyruvate to ADP, forming ATP and pyruvate. This is one of the two substrate-level phosphorylations of glycolysis.

Question 8Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 45-year-old man is unable to abduct his arm beyond 15 degrees after a shoulder injury. Which muscle is most likely paralysed?

  1. Latissimus dorsi
  2. Teres major
  3. Pectoralis major
  4. Deltoid Correct answer.

Explanation

The deltoid, supplied by the axillary nerve, is the principal abductor of the arm from 15 to 90 degrees. Its paralysis causes loss of abduction, often with sensory loss over the lateral shoulder.

Question 9Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with a lesion of the left recurrent laryngeal nerve develops hoarseness. Which structure is most likely responsible for the nerve's vulnerability on the left side?

  1. The right subclavian artery
  2. The thyroid cartilage
  3. The cricothyroid muscle
  4. The arch of the aorta Correct answer.

Explanation

The left recurrent laryngeal nerve loops under the arch of the aorta at the ligamentum arteriosum, so aortic disease or aneurysm can compress it. The right recurrent nerve loops under the right subclavian artery instead.

Question 10Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient presents with polyuria, polydipsia and hypernatraemia after head trauma. Serum ADH is low. Which part of the pituitary is most likely damaged?

  1. Anterior pituitary
  2. Hypophyseal portal system
  3. Posterior pituitary Correct answer.
  4. Pars intermedia

Explanation

ADH is synthesised in hypothalamic supraoptic and paraventricular neurons and released from axon terminals in the posterior pituitary. Damage to this region causes central diabetes insipidus with dilute urine and hypernatraemia.

Question 11Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A muscle biopsy shows accumulation of glycogen with normal branching but absent muscle phosphorylase activity. Which glycogen storage disease is this?

  1. Von Gierke disease
  2. Cori disease
  3. Pompe disease
  4. McArdle disease Correct answer.

Explanation

McArdle disease results from deficiency of muscle glycogen phosphorylase (myophosphorylase), so glycogen accumulates in skeletal muscle with normal structure. Patients develop exercise intolerance, cramps and myoglobinuria.

Question 12Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which change in the oxygen-haemoglobin dissociation curve is expected in a patient with increased 2,3-BPG, such as in chronic anaemia?

  1. Shift to the right with decreased oxygen affinity Correct answer.
  2. No change in curve position
  3. Shift to the right with increased oxygen affinity
  4. Shift to the left with increased oxygen affinity

Explanation

Raised 2,3-BPG binds deoxyhaemoglobin and stabilises the T state, lowering oxygen affinity. This shifts the curve to the right and enhances unloading of oxygen to tissues.

Question 13Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 30-year-old woman has episodes of muscle weakness with hypokalaemia and hypertension. Aldosterone is elevated despite suppressed renin. Which enzyme defect is most likely?

  1. 11-beta-hydroxylase Correct answer.
  2. 21-hydroxylase
  3. Aldosterone synthase
  4. 17-alpha-hydroxylase

Explanation

11-beta-hydroxylase deficiency shunts precursors into the mineralocorticoid pathway, producing deoxycorticosterone excess with hypertension, hypokalaemia and suppressed renin. Androgen excess also causes virilisation in females.

Question 14Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient sustains a lesion of the left optic tract. Which visual field defect is expected?

  1. Bitemporal hemianopia
  2. Left monocular blindness
  3. Left homonymous hemianopia
  4. Right homonymous hemianopia Correct answer.

Explanation

The left optic tract carries fibres from the temporal retina of the left eye and nasal retina of the right eye, which correspond to the right visual field. A lesion therefore produces a right homonymous hemianopia.

Question 15Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which amino acid is the precursor for serotonin synthesis in the brain?

  1. Tryptophan Correct answer.
  2. Histidine
  3. Glutamate
  4. Tyrosine

Explanation

Tryptophan is hydroxylated and decarboxylated to form serotonin by tryptophan hydroxylase and aromatic amino acid decarboxylase. Its availability in the brain depends on dietary intake and transport across the blood-brain barrier.

Question 16Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient's spirometry shows FEV1/FVC of 0.55 with increased total lung capacity. Which pattern of lung disease does this indicate?

  1. Normal pattern
  2. Mixed pattern with reduced TLC
  3. Obstructive pattern Correct answer.
  4. Restrictive pattern

Explanation

A reduced FEV1/FVC ratio below 0.70 defines airflow obstruction, and the increased total lung capacity indicates hyperinflation typical of emphysema. Restrictive disease instead shows a normal or raised ratio with reduced total lung capacity.

Question 17Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which structure passes through the foramen ovale of the sphenoid bone?

  1. Optic nerve
  2. Middle meningeal artery
  3. Maxillary division of the trigeminal nerve
  4. Mandibular division of the trigeminal nerve Correct answer.

Explanation

The foramen ovale transmits the mandibular division of the trigeminal nerve along with the accessory meningeal artery and lesser petrosal nerve. It lies in the greater wing of the sphenoid.

Question 18Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A child with severe combined immunodeficiency has a defect in the common gamma chain shared by several cytokine receptors. Which signalling pathway is most directly impaired?

  1. Adenylyl cyclase pathway
  2. JAK-STAT pathway Correct answer.
  3. Phospholipase C pathway
  4. TGF-beta Smad pathway

Explanation

The common gamma chain associates with JAK3, which phosphorylates STAT proteins after cytokine binding. Loss of this chain impairs interleukin signalling through the JAK-STAT pathway, causing X-linked severe combined immunodeficiency.

Question 19Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with a cerebellar lesion shows intention tremor and dysdiadochokinesia. Which cerebellar region is most likely affected?

  1. Fastigial nucleus
  2. Neocerebellum Correct answer.
  3. Flocculonodular lobe
  4. Vermis

Explanation

The neocerebellum, comprising the lateral cerebellar hemispheres, coordinates voluntary limb movement and is connected with the cerebral cortex. Its lesions produce intention tremor, dysmetria and dysdiadochokinesia.

Question 20Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which enzyme catalyses the rate-limiting step of cholesterol biosynthesis?

  1. HMG-CoA reductase Correct answer.
  2. HMG-CoA synthase
  3. Squalene epoxidase
  4. Mevalonate kinase

Explanation

HMG-CoA reductase converts HMG-CoA to mevalonate and is the principal regulated step of cholesterol synthesis. It is the target of statins and is inhibited by cholesterol through feedback.

Question 21Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with a pituitary adenoma develops bitemporal hemianopia. Which anatomical relationship explains this finding?

  1. The optic chiasm lies above the pituitary fossa, so crossing nasal fibres are compressed. Correct answer.
  2. The optic tract runs through the pituitary fossa.
  3. The optic nerve is compressed within the optic canal.
  4. The lateral geniculate body is compressed by the tumour.

Explanation

The optic chiasm sits superior to the sella turcica, so an expanding pituitary tumour compresses crossing fibres from the nasal retina. These fibres subserve the temporal visual fields, producing bitemporal hemianopia.

Question 22Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A patient with chronic alcoholism develops Wernicke encephalopathy. Which enzyme deficiency in thiamine metabolism predisposes to this condition?

  1. Branched-chain ketoacid dehydrogenase
  2. Transketolase Correct answer.
  3. Alpha-ketoglutarate dehydrogenase
  4. Pyruvate dehydrogenase

Explanation

Thiamine pyrophosphate is a cofactor for transketolase in the pentose phosphate pathway, and its activity in erythrocytes is used to diagnose thiamine deficiency. However, the classical diagnostic enzyme test is transketolase activity, while neurological features arise from impaired pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase.

Question 23Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

Which hormone is primarily responsible for the preovulatory surge of luteinising hormone?

  1. Prolactin
  2. Oestradiol Correct answer.
  3. Progesterone
  4. Inhibin

Explanation

Rising oestradiol from the dominant follicle exerts positive feedback on the hypothalamus and anterior pituitary at mid-cycle. This triggers the LH surge that induces ovulation.

Question 24Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A newborn with ambiguous genitalia has hyponatraemia, hyperkalaemia and hypotension. Which enzyme deficiency is most likely?

  1. 17-alpha-hydroxylase
  2. 3-beta-hydroxysteroid dehydrogenase
  3. 11-beta-hydroxylase
  4. 21-hydroxylase Correct answer.

Explanation

21-hydroxylase deficiency is the commonest cause of congenital adrenal hyperplasia and impairs both cortisol and aldosterone synthesis. Aldosterone deficiency causes salt wasting with hyponatraemia and hyperkalaemia, while androgen excess virilises female genitalia.

Question 25Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

During the cardiac cycle, which event coincides with the second heart sound?

  1. Closure of the atrioventricular valves
  2. Atrial contraction
  3. Closure of the semilunar valves Correct answer.
  4. Opening of the atrioventricular valves

Explanation

The second heart sound is produced by closure of the aortic and pulmonary semilunar valves at the end of ventricular systole. The first heart sound instead results from closure of the mitral and tricuspid valves.

Question 26Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 22-year-old man sustains a penetrating injury to the medial aspect of his forearm. He is unable to flex the distal phalanx of the little finger. Which nerve is most likely injured?

  1. Ulnar nerve Correct answer.
  2. Median nerve
  3. Radial nerve
  4. Anterior interosseous nerve

Explanation

The ulnar nerve supplies the flexor digitorum profundus to the little and ring fingers via its muscular branches in the forearm. Injury leads to loss of flexion at the distal interphalangeal joint of the little finger. The median nerve and its anterior interosseous branch supply the other digits, while the radial nerve is primarily an extensor.

Question 27Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 60-year-old man with chronic obstructive pulmonary disease has an arterial blood gas showing pH 7.32, PaCO2 60 mmHg, and HCO3- 30 mEq/L. Which acid-base disturbance is most likely?

  1. Chronic respiratory acidosis with metabolic compensation Correct answer.
  2. Metabolic alkalosis with respiratory compensation
  3. Acute respiratory acidosis without metabolic compensation
  4. Mixed respiratory and metabolic acidosis

Explanation

The elevated PaCO2 indicates respiratory acidosis. The bicarbonate of 30 mEq/L is elevated, reflecting renal compensation that takes days to develop, consistent with a chronic process. In acute respiratory acidosis, bicarbonate would be only minimally elevated.

Question 28Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 3-year-old child presents with recurrent infections, eczema, and thrombocytopenia. Blood smear shows small platelets. Flow cytometry reveals absent Wiskott-Aldrich syndrome protein (WASP). Which mode of inheritance is expected for this disorder?

  1. Autosomal recessive
  2. X-linked recessive Correct answer.
  3. Mitochondrial
  4. Autosomal dominant

Explanation

Wiskott-Aldrich syndrome is caused by mutations in the WAS gene located on the X chromosome, so it is inherited in an X-linked recessive pattern. This explains why it primarily affects males. The other inheritance patterns do not fit the typical presentation and genetic basis.

Question 29Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 45-year-old woman with a history of gallstones presents with severe epigastric pain radiating to the back. Serum amylase is markedly elevated. Which enzyme is most likely responsible for the autodigestion of pancreatic tissue in this condition?

  1. Elastase
  2. Chymotrypsin
  3. Trypsin Correct answer.
  4. Phospholipase A2

Explanation

In acute pancreatitis, premature activation of trypsinogen to trypsin within the pancreas triggers a cascade that activates other digestive enzymes, leading to autodigestion. Trypsin is the key initiator. The other enzymes are activated by trypsin but are not the primary trigger.

Question 30Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 28-year-old woman has a fasting blood glucose of 7.8 mmol/L and a HbA1c of 6.8%. She is asymptomatic. Which additional test is required to confirm a diagnosis of diabetes mellitus according to WHO criteria?

  1. Repeat fasting plasma glucose Correct answer.
  2. Oral glucose tolerance test
  3. Random plasma glucose
  4. Fructosamine level

Explanation

WHO criteria require a second abnormal test to confirm diabetes in an asymptomatic individual unless the initial result is unequivocal (e.g., random glucose ≥11.1 mmol/L with symptoms). A repeat fasting plasma glucose is the standard confirmatory test. The other tests are not the first-line confirmation in this scenario.

Question 31Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 55-year-old man with hypertension and hypokalemia is found to have an adrenal adenoma. His aldosterone is elevated and renin is suppressed. Which enzyme is most directly responsible for the increased aldosterone synthesis?

  1. Aldosterone synthase Correct answer.
  2. 17α-hydroxylase
  3. 21-hydroxylase
  4. 11β-hydroxylase

Explanation

Aldosterone synthase catalyzes the final step of aldosterone biosynthesis in the zona glomerulosa. In primary aldosteronism, its activity is increased, leading to elevated aldosterone. The other enzymes are involved in cortisol and androgen synthesis and their deficiencies cause different patterns.

Question 32Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 32-year-old woman presents with fatigue, weight gain, and cold intolerance. Laboratory tests show elevated TSH and low free T4. Which of the following is the most likely underlying mechanism?

  1. Thyroid hormone resistance
  2. Iodine deficiency
  3. Autoimmune destruction of thyroid follicular cells Correct answer.
  4. Pituitary adenoma secreting TSH

Explanation

The combination of elevated TSH and low free T4 indicates primary hypothyroidism. The most common cause in iodine-sufficient areas is Hashimoto's thyroiditis, an autoimmune destruction of the thyroid gland. This leads to failure of hormone production and a compensatory rise in TSH.

Question 33Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 50-year-old man with alcohol use disorder presents with confusion and ataxia. MRI shows atrophy of the cerebellar vermis. Which vitamin deficiency is most likely responsible?

  1. Vitamin B12 (cobalamin)
  2. Vitamin E (tocopherol)
  3. Vitamin B1 (thiamine) Correct answer.
  4. Vitamin B6 (pyridoxine)

Explanation

Thiamine deficiency is common in alcohol use disorder and can cause Wernicke-Korsakoff syndrome and cerebellar degeneration, particularly affecting the vermis. This leads to ataxia and confusion. The other vitamins are not classically associated with this specific pattern.

Question 34Pre-clinical subjects (Anatomy, Physiology, Biochemistry)

A 60-year-old man with a history of myocardial infarction has an echocardiogram showing a left ventricular ejection fraction of 30%. Which compensatory mechanism is most directly responsible for maintaining his cardiac output?

  1. Baroreceptor reflex
  2. Sympathetic nervous system
  3. Frank-Starling mechanism Correct answer.
  4. Renin-angiotensin-aldosterone system

Explanation

The Frank-Starling mechanism refers to the heart's ability to increase stroke volume in response to increased preload (ventricular filling). In heart failure with reduced ejection fraction, increased preload helps maintain cardiac output acutely. The other mechanisms are also activated but are not the direct intrinsic compensation for reduced contractility.

Question 35Pathology

A 24-year-old man develops fever, jaundice, and right upper quadrant pain three weeks after a bout of gastroenteritis. Liver biopsy shows flask-shaped microabscesses containing trophozoites. Which organism is most likely responsible?

  1. Balantidium coli
  2. Cryptosporidium parvum
  3. Entamoeba histolytica Correct answer.
  4. Giardia lamblia

Explanation

Entamoeba histolytica reaches the liver through the portal vein after colonic invasion and produces the classic 'anchovy sauce' flask-shaped hepatic abscess. Trophozoites with ingested red cells are seen at the abscess wall. Giardia and Cryptosporidium remain confined to the intestinal lumen and do not cause hepatic abscesses.

Question 36Pathology

Which morphological change is the earliest light-microscopic hallmark of reversible cell injury?

  1. Karyorrhexis of the nucleus
  2. Rupture of the plasma membrane
  3. Cellular swelling with blebbing of the plasma membrane Correct answer.
  4. Calcification of mitochondria

Explanation

Hydropic swelling due to failure of the ATP-dependent Na+/K+ pump is the first visible sign of reversible injury. Nuclear changes such as karyorrhexis and membrane rupture denote irreversible injury. Dystrophic calcification of mitochondria occurs later in necrotic cells.

Question 37Pathology

A 58-year-old smoker presents with hemoptysis. Biopsy of a central bronchial mass shows nests of cells with keratin pearls and intercellular bridges. Which tumor marker is most likely elevated?

  1. CA 19-9
  2. Carcinoembryonic antigen Correct answer.
  3. Alpha-fetoprotein
  4. Calcitonin

Explanation

The histology describes squamous cell carcinoma of the lung, which is associated with elevated carcinoembryonic antigen and CYFRA 21-1. Alpha-fetoprotein marks hepatocellular and yolk sac tumors, CA 19-9 marks pancreatic and biliary tumors, and calcitonin marks medullary thyroid carcinoma.

Question 38Pathology

A 30-year-old woman has a butterfly rash, photosensitivity, and arthralgia. Which autoantibody is most specific for this condition?

  1. Anti-double-stranded DNA Correct answer.
  2. Anti-Scl-70
  3. Anti-histone
  4. Anti-centromere

Explanation

Anti-double-stranded DNA antibodies are highly specific for systemic lupus erythematosus and correlate with disease activity and lupus nephritis. Anti-histone antibodies suggest drug-induced lupus, anti-centromere antibodies suggest limited cutaneous scleroderma, and anti-Scl-70 suggests diffuse scleroderma.

Question 39Pathology

A 45-year-old man with chronic hepatitis B develops a large liver mass. Serum alpha-fetoprotein is markedly elevated. Which microscopic feature best supports the diagnosis?

  1. Nests of small blue round cells with rosettes
  2. Glandular acini lined by mucin-secreting cells
  3. Trabeculae of hepatocytes separated by sinusoidal endothelial cells Correct answer.
  4. Papillary fronds with psammoma bodies

Explanation

Hepatocellular carcinoma classically shows a trabecular pattern in which malignant hepatocytes are arranged in plates separated by sinusoids lined by endothelial cells. Mucinous glands indicate cholangiocarcinoma or metastatic adenocarcinoma. Small blue round cells and psammoma bodies belong to other tumor types.

Question 40Pathology

Which type of hypersensitivity reaction underlies acute hemolytic transfusion reactions?

  1. Type IV T-cell-mediated delayed hypersensitivity
  2. Type I IgE-mediated anaphylaxis
  3. Type II antibody-mediated cytotoxicity Correct answer.
  4. Type III immune complex deposition

Explanation

Preformed antibodies bind to donor red cell antigens and activate complement, causing intravascular hemolysis, which is a type II reaction. Type I involves IgE and mast cells, type III involves immune complex deposition, and type IV is T-cell mediated.

Question 41Pathology

A 62-year-old man has a 3 cm nodule in the thyroid with amyloid stroma and calcitonin positivity. Which syndrome should prompt screening for a RET germline mutation?

  1. Multiple endocrine neoplasia type 2 Correct answer.
  2. von Hippel-Lindau disease
  3. Neurofibromatosis type 1
  4. Multiple endocrine neoplasia type 1

Explanation

The tumor described is medullary thyroid carcinoma, which occurs sporadically or as part of MEN 2 caused by activating RET mutations. MEN 2 also includes pheochromocytoma and parathyroid hyperplasia. MEN 1 involves pituitary, parathyroid, and pancreatic tumors, and VHL and NF1 are unrelated to medullary thyroid carcinoma.

Question 42Pathology

Which of the following best describes the pathogenesis of coagulative necrosis?

  1. Caseous friable material with granulomatous rim
  2. Enzymatic digestion of tissue leading to a cyst
  3. Denaturation of structural and enzymatic proteins with preservation of tissue architecture Correct answer.
  4. Fibrinoid deposition in vessel walls

Explanation

Coagulative necrosis results from ischemia, where acidosis denatures proteins and blocks enzymatic digestion, preserving the outline of the tissue for days. Liquefactive necrosis involves enzymatic digestion, caseous necrosis is typical of tuberculosis, and fibrinoid necrosis occurs in immune-mediated vasculitis.

Question 43Pathology

A 55-year-old woman has a breast mass. Microscopy shows nests of cells within a myxoid stroma with a 'pushing' border and no glandular differentiation. Which molecular alteration most characteristically underlies this lesion?

  1. t(8;14) MYC translocation
  2. t(9;22) BCR-ABL translocation
  3. t(12;16) FUS-DDIT3 translocation Correct answer.
  4. t(11;22) EWSR1-FLI1 translocation

Explanation

The description fits myxoid liposarcoma, which carries the t(12;16) translocation fusing FUS with DDIT3. The MYC translocation occurs in Burkitt lymphoma, EWSR1-FLI1 in Ewing sarcoma, and BCR-ABL in chronic myeloid leukemia.

Question 44Pathology

A 3-year-old child presents with fever, pallor, and bone pain. Peripheral smear shows many lymphoblasts, and flow cytometry shows terminal deoxynucleotidyl transferase positivity. What is the most likely diagnosis?

  1. Acute lymphoblastic leukemia Correct answer.
  2. Acute myeloid leukemia
  3. Infectious mononucleosis
  4. Chronic lymphocytic leukemia

Explanation

Childhood acute lymphoblastic leukemia presents with marrow failure and bone pain, and blasts are TdT-positive, reflecting immature lymphoid cells. Acute myeloid leukemia blasts are myeloperoxidase-positive and TdT-negative. Chronic lymphocytic leukemia occurs in older adults, and infectious mononucleosis shows atypical lymphocytes rather than blasts.

Question 45Pathology

A 68-year-old man has a colonic polyp showing elongated, hyperchromatic nuclei with a saw-toothed architecture but no dysplasia. Which lesion is described?

  1. Adenocarcinoma
  2. Tubular adenoma
  3. Villous adenoma
  4. Hyperplastic polyp Correct answer.

Explanation

Hyperplastic polyps have serrated crypts with hyperchromatic nuclei but no dysplasia and carry minimal malignant potential. Adenomas show dysplastic epithelium, and adenocarcinoma shows invasion through the muscularis mucosae.

Question 46Pathology

Which of the following is the primary mechanism of action of tumor necrosis factor inhibitors used in rheumatoid arthritis?

  1. Neutralization of soluble and membrane-bound TNF Correct answer.
  2. Blockade of B-cell CD20 receptors
  3. Inhibition of dihydrofolate reductase
  4. Inhibition of cyclooxygenase enzymes

Explanation

TNF inhibitors bind and neutralize TNF, reducing synovial inflammation in rheumatoid arthritis. Cyclooxygenase inhibition describes NSAIDs, CD20 blockade describes rituximab, and dihydrofolate reductase inhibition describes methotrexate.

Question 47Pathology

A 40-year-old man has a testicular mass. Histology shows a uniform population of cells with clear cytoplasm, distinct cell membranes, and fibrous septa containing lymphocytes. Which tumor is most likely?

  1. Seminoma Correct answer.
  2. Leydig cell tumor
  3. Yolk sac tumor
  4. Embryonal carcinoma

Explanation

Seminoma is characterized by uniform cells with clear glycogen-rich cytoplasm, distinct borders, and fibrous septa infiltrated by lymphocytes. Yolk sac tumors show Schiller-Duval bodies, embryonal carcinoma shows pleomorphic cells with hemorrhage and necrosis, and Leydig cell tumors show Reinke crystals.

Question 48Pathology

A 28-year-old woman has a firm, mobile thyroid nodule. Fine needle aspiration shows papillary structures with optically clear nuclei and nuclear grooves. Which feature is most characteristic on histology?

  1. Hurthle cell change with abundant eosinophilic cytoplasm
  2. Orphan Annie eye nuclei Correct answer.
  3. Psammoma bodies in a follicular pattern
  4. Amyloid stroma

Explanation

Papillary thyroid carcinoma shows optically clear 'Orphan Annie eye' nuclei with grooves and pseudoinclusions. Psammoma bodies may be present but the nuclear features are diagnostic. Amyloid stroma indicates medullary carcinoma, and Hurthle cell change indicates a Hurthle cell neoplasm.

Question 49Pathology

Which of the following is the most important prognostic factor in breast carcinoma?

  1. Estrogen receptor positivity
  2. Tumor grade alone
  3. Axillary lymph node status Correct answer.
  4. Patient age

Explanation

Axillary lymph node involvement is the single strongest prognostic factor in breast carcinoma, followed by tumor size and histologic grade. Receptor status guides therapy but is not the primary prognostic determinant.

Question 50Pathology

A 60-year-old man with long-standing gastroesophageal reflux undergoes biopsy of the distal esophagus. Histology shows columnar epithelium with goblet cells. What is the diagnosis?

  1. Squamous cell carcinoma
  2. Achalasia
  3. Barrett esophagus Correct answer.
  4. Eosinophilic esophagitis

Explanation

Barrett esophagus is intestinal metaplasia of the distal esophagus, defined by goblet cells in columnar epithelium, and predisposes to adenocarcinoma. Squamous cell carcinoma shows malignant squamous cells, achalasia shows aperistalsis without metaplasia, and eosinophilic esophagitis shows intraepithelial eosinophils.