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I have all 40 questions extracted. These are all standard pathology MCQs that I can answer confidently from knowledge. Let me provide complete answers now.
MCQ Answers
Section I-XX (Internal Assessment Set)
I. A 22-year-old girl with an infected wound - bacteria removed by which extravascular cell?
Answer: B. Macrophage
Macrophages are the primary phagocytic cells in extravascular tissue. They engulf and destroy bacteria via phagocytosis. Mast cells are involved in allergic/inflammatory signaling; T and B lymphocytes deal with adaptive immunity, not direct bacterial killing.
II. Massive heart attack, death at 24 hours - which inflammatory cells predominate?
Answer: A. Neutrophils
In acute myocardial infarction, neutrophils are the first responders and dominate the inflammatory infiltrate between 12-72 hours. Macrophages predominate later (3-7 days).
III. Mitral stenosis patient - "heart failure cells" in the lung represent:
Answer: C. Macrophages laden with hemosiderin pigment
Heart failure cells are alveolar macrophages engorged with hemosiderin from extravasated RBCs in pulmonary congestion (left-sided heart failure - mitral stenosis causes left-sided back pressure). They stain positive with Prussian blue.
IV. Post-surgery patient dies of pulmonary thromboembolism - most likely cause:
Answer: B. Deep Vein Thrombosis (DVT)
Post-surgical immobility is a classic risk factor for DVT. Pulmonary thromboembolism originates from DVT (most commonly from deep veins of legs/pelvis) in ~95% of cases. This is Virchow's triad in action (stasis, hypercoagulability, endothelial injury).
V. Blood group A+ patient given B+ blood - intravascular hemolysis mechanism:
Answer: D. Antibody-mediated complement fixation
ABO incompatibility is a Type II hypersensitivity reaction. Anti-B IgM antibodies (naturally occurring) in the A+ patient bind B antigens on donor RBCs and activate complement, leading to intravascular hemolysis via the membrane attack complex.
VI. Starving 4-year-old with edema, fatty liver, preserved subcutaneous fat:
Answer: B. Kwashiorkor
Classic features of kwashiorkor: generalized edema (due to hypoalbuminemia), fatty liver, preserved subcutaneous fat (adequate calories, protein deficient). Marasmus shows wasting of both fat and muscle with no edema.
VII. 3-year-old with microcytic hypochromic anemia, normal serum iron, hepatosplenomegaly, skull X-ray with expanded marrow spaces:
Answer: B. Quantitative defect of Beta globin chain
This is Beta-thalassemia major. Key clues: severe microcytic hypochromic anemia, normal/high serum iron (ruling out iron deficiency), hepatosplenomegaly (extramedullary hematopoiesis), skull changes ("hair-on-end" appearance) from marrow expansion, high reticulocyte count.
VIII. Most common lab finding in hypersplenism:
Answer: B. Thrombocytopenia
Hypersplenism causes sequestration and destruction of blood cells. While all cell lines can be affected (pancytopenia), thrombocytopenia is the most commonly and prominently associated finding.
IX. Genetic abnormality most commonly associated with CML:
Answer: B. t(9;22) translocation
The t(9;22) is the Philadelphia chromosome - BCR-ABL fusion gene. This is pathognomonic of CML. [t(8;14) = Burkitt's lymphoma; t(14;18) = Follicular lymphoma; JAK2 mutation = Polycythemia vera/myeloproliferative disorders]
X. Most sensitive tissue to hypoxia - undergoes necrosis in 3-4 minutes:
Answer: A. Neurons
Neurons (especially in the cerebral cortex and hippocampus) are the most sensitive to hypoxia due to their high metabolic demand and inability to use anaerobic glycolysis effectively. Irreversible damage occurs within 3-5 minutes of ischemia.
XI. Opsonization is:
Answer: B. Coating of antigen by antibody
Opsonization is the process by which antigens (especially bacteria) are coated with opsonins (antibodies - IgG, and complement - C3b) to enhance their recognition and phagocytosis by neutrophils and macrophages.
XII. Most characteristic microscopic feature of anaplasia in malignant tumors:
Answer: C. Loss of polarity and atypical mitotic figures
Anaplasia (lack of differentiation) is characterized by: pleomorphism, high N:C ratio (not low), loss of normal architecture/polarity, abnormal (atypical) mitotic figures, prominent nucleoli. Options A, B, D all describe well-differentiated/benign features.
XIII. Ozone toxicity as an air pollutant:
Answer: B. It produces free radicals that damage respiratory tract cells
Ozone (O₃) is a powerful oxidant. It reacts with biological molecules to generate reactive oxygen species (free radicals), causing oxidative damage to respiratory epithelium, leading to inflammation, airway hyperreactivity, and reduced lung function. (CO binds hemoglobin, not ozone.)
XIV. Distinguishing microscopic feature of antemortem thrombi:
Answer: A. Presence of lines of Zahn
Lines of Zahn are alternating pale layers (platelets + fibrin) and dark layers (RBCs) in thrombi formed during life (antemortem) due to flowing blood. Postmortem clots are uniform and lack these lines.
XV. Laboratory profile most consistent with iron deficiency anemia:
Answer: A. Serum Iron low, TIBC high, serum ferritin low
Iron deficiency: low serum iron (depleted stores), high TIBC (body upregulates transferrin to "capture" more iron), low ferritin (best marker of depleted stores). This is the classic triad.
XVI. Autoimmune condition with megaloblastic anemia due to destruction of gastric parietal cells:
Answer: A. Pernicious anemia
Pernicious anemia is caused by autoimmune destruction of gastric parietal cells, leading to failure of intrinsic factor production, inability to absorb vitamin B12, and resultant megaloblastic anemia.
XVII. 5-year-old boy with fever, pallor, bone tenderness, petechiae, anemia, thrombocytopenia, PAS-positive blasts:
Answer: B. Acute Lymphoblastic Leukemia (ALL)
Classic presentation of ALL in children. PAS-positive blasts are lymphoblasts (glycogen-rich). Bone tenderness from marrow infiltration, pancytopenia from marrow replacement. ALL is the most common childhood malignancy.
XVIII. Correct statement about Sago spleen and Lardaceous spleen:
Answer: C. Sago spleen appears as tapioca-like granules in the white pulp
- Sago spleen: amyloid deposits in white pulp (Malpighian corpuscles) - appears as grey, semi-translucent granules resembling sago/tapioca
- Lardaceous spleen: diffuse amyloid in red pulp - gives a waxy, lard-like appearance throughout Option A is wrong (it's in white pulp); B and D are wrong (lardaceous = red pulp, diffuse)
XIX. Histopathological feature characteristic of Basal Cell Carcinoma (BCC):
Answer: B. Peripheral palisading of tumor cells
BCC shows characteristic peripheral palisading (nuclear palisading at the periphery of tumor nests) with retraction artifact. Keratin pearls = squamous cell carcinoma; Pagetoid spread = Paget's disease/melanoma; Intercellular bridges = squamous cell carcinoma.
XX. 7-year-old with petechiae, ecchymoses, platelets 12,500/cu.mm, normal Hb, increased megakaryocytes in bone marrow:
Answer: B. Immune Thrombocytopenic Purpura (ITP)
Key features: isolated thrombocytopenia (normal Hb rules out aplastic anemia), INCREASED megakaryocytes in bone marrow (ITP destroys platelets in the periphery, so marrow compensates by increasing megakaryocytes - this distinguishes ITP from aplastic anemia where megakaryocytes are decreased). Normal coagulation rules out DIC/hemophilia.
Section 1-20 (Second Set)
1. Most common cause of death immediately following acute MI:
Answer: c) Arrhythmia (e.g., ventricular fibrillation)
Ventricular fibrillation/arrhythmia is the leading cause of sudden death in the immediate period after MI (within the first hour). Cardiogenic shock and LV failure are later complications.
2. Lung cancer most strongly associated with smoking:
Answer: b) Small Cell Carcinoma
Small cell carcinoma (oat cell carcinoma) has the strongest association with smoking (>95% of cases occur in smokers). It arises from Kulchitsky cells (neuroendocrine), is centrally located, and is the most aggressive. Note: Squamous cell carcinoma also has a very strong smoking association; among the options, Small Cell is correct.
3. Key morphological feature of Centriacinar (Centrilobular) Emphysema:
Answer: b) Destruction of respiratory bronchioles, spares distal alveoli
Centriacinar emphysema (most common type, caused by smoking) affects the central/proximal part of the acinus - the respiratory bronchioles are destroyed while the distal alveoli are initially spared. Panacinar emphysema (Alpha-1 AT deficiency) destroys the entire acinus.
4. Bilateral enlarged cystic kidneys, mild raised creatinine, hematuria - most common genetic mutation:
Answer: (a) PKD 1 gene mutation
Adult polycystic kidney disease (ADPKD) - PKD1 mutation on chromosome 16 accounts for ~85% of cases; PKD2 (chromosome 4) accounts for ~15%. PKD1 has earlier onset and more severe disease.
5. Postmenopausal bleeding, complex proliferation of endometrial glands with nuclear atypia:
Answer: c) Endometrial hyperplasia with atypia
Complex endometrial hyperplasia with atypia (now called endometrial intraepithelial neoplasia) is characterized by crowded, complex glands with nuclear atypia. It has significant risk of progression to endometrial carcinoma.
6. Anticoagulant for complete blood count (CBC) sample:
Answer: a) EDTA
EDTA (ethylenediaminetetraacetic acid) is the anticoagulant of choice for CBC. It preserves cell morphology and prevents platelet clumping. Purple/lavender-top tubes. [Sodium fluoride = glucose; Trisodium citrate = coagulation tests; Heparin = some chemistry tests]
7. Thyroid carcinoma with best prognosis:
Answer: a) Papillary carcinoma
Papillary thyroid carcinoma has the best prognosis (10-year survival >95%). It spreads to cervical lymph nodes but rarely metastasizes distantly. Anaplastic carcinoma has the worst prognosis (median survival ~6 months).
8. Breast lump histology (without image, based on options):
Answer: d) Fibroadenoma - Intracanalicular pattern
Without the image, the most common breast fibroadenoma pattern in young women. Intracanalicular pattern: stroma compresses ducts into slit-like spaces. Pericanalicular: stroma surrounds round/oval ducts. (If the image shows compressed slit-like ducts with abundant stroma = intracanalicular; if round ducts = pericanalicular. This question requires the histology image.)
Note: Question 8 references a histology image that was not available in the PDF text. The answer depends on the actual image shown. If the ducts are compressed into irregular slit-like spaces by fibrous stroma, it is (d) Intracanalicular. If ducts retain round/oval shape with concentric stroma, it is (c) Pericanalicular.
9. Stellate granuloma is seen in:
Answer: c) Cat-scratch disease
Stellate (star-shaped) granulomas with central necrosis are characteristic of cat-scratch disease (Bartonella henselae). Sarcoidosis shows non-caseating granulomas; tuberculosis shows caseating granulomas; malignancy does not typically form stellate granulomas.
10. Dwarf female with primary amenorrhea, webbed neck, widely spaced nipples - most common monosomy:
Answer: c) 45XO
This is Turner syndrome (45,X or 45XO). Features: short stature, primary amenorrhea, webbed neck, shield chest with widely spaced nipples, coarctation of aorta. 47XXY = Klinefelter syndrome (male).
11. Translocation in CML:
Answer: b) t(9;22)
Same as Question IX above - Philadelphia chromosome t(9;22)(q34;q11) producing BCR-ABL fusion gene. t(15;17) = APL (AML-M3); t(14;18) = Follicular lymphoma.
12. Prototypical disorder of Type IV hypersensitivity:
Answer: d) Tuberculosis
Type IV (delayed-type/cell-mediated) hypersensitivity is mediated by T lymphocytes, not antibodies. Tuberculosis (and the tuberculin skin test) is the classic example. [Anaphylaxis = Type I; Goodpasture = Type II; SLE = Type III]
13. Crushing chest pain for 4 hours, ST elevation - most useful serum test:
Answer: c) Troponin T and I
Cardiac troponins (cTnT and cTnI) are the gold standard biomarkers for myocardial infarction. They are highly specific for cardiac muscle injury, rise within 3-6 hours, peak at 24-48 hours, and remain elevated for 7-14 days.
14. Fever, night sweats, weight loss, hemoptysis, cavitary lesion in upper lobe:
Answer: c) Mycobacterium tuberculosis
Classic presentation of pulmonary TB: constitutional symptoms (fever, night sweats, weight loss - "B symptoms"), hemoptysis, cavitary lesion in the upper lobes (favored by high O₂ tension). Legionella = atypical pneumonia without cavities; Mycoplasma = walking pneumonia.
15. Chronic alcoholic with enlarged liver and raised AFP:
Answer: a) Hepatocellular carcinoma (HCC)
Chronic alcoholism → liver cirrhosis → HCC. Raised AFP (alpha-fetoprotein) is a tumor marker strongly associated with HCC. Hepatomegaly + cirrhosis background + elevated AFP = HCC until proven otherwise.
16. Organism most associated with chronic gastritis:
Answer: b) Helicobacter pylori
H. pylori is the most common cause of chronic active gastritis (type B gastritis), affecting the antrum predominantly. It is also associated with peptic ulcer disease and gastric carcinoma. It is the most common bacterial infection in humans.
17. Mature cystic teratoma of ovary most commonly arises from:
Answer: b) Germ Cells
Mature cystic teratoma (dermoid cyst) is the most common benign ovarian tumor. It arises from germ cells (totipotent), hence contains tissues from all three germ layers (ectoderm, mesoderm, endoderm) - skin, hair, teeth, etc.
18. Child with nephrotic syndrome, normal light microscopy, electron microscopy shows foot process fusion:
Answer: c) Minimal Change Disease (MCD)
Minimal change disease is defined by: normal light microscopy, normal immunofluorescence, but diffuse effacement (fusion) of podocyte foot processes on EM. It is the most common cause of nephrotic syndrome in children and responds well to steroids.
19. "Starry sky" pattern is seen in:
Answer: a) Burkitt's lymphoma
The "starry sky" pattern in Burkitt's lymphoma is produced by scattered pale-staining macrophages (the "stars") engulfing apoptotic tumor cells against a dark background of densely packed lymphoma cells (the "sky"). It reflects a very high proliferation rate.
20. Carcinoid tumor develops from:
Answer: b) Kulchitsky cells
Carcinoid tumors (well-differentiated neuroendocrine tumors) arise from Kulchitsky cells (enterochromaffin cells) - neuroendocrine cells of the gut lining. They produce serotonin and other vasoactive substances causing carcinoid syndrome.
Quick Reference Answer Key
| # | Answer | # | Answer | |
|---|---|---|---|---|
| I | B | XI | B | |
| II | A | XII | C | |
| III | C | XIII | B | |
| IV | B | XIV | A | |
| V | D | XV | A | |
| VI | B | XVI | A | |
| VII | B | XVII | B | |
| VIII | B | XVIII | C | |
| IX | B | XIX | B | |
| X | A | XX | B |
| # | Answer | # | Answer | |
|---|---|---|---|---|
| 1 | c | 11 | b | |
| 2 | b | 12 | d | |
| 3 | b | 13 | c | |
| 4 | a | 14 | c | |
| 5 | c | 15 | a | |
| 6 | a | 16 | b | |
| 7 | a | 17 | b | |
| 8 | See note* | 18 | c | |
| 9 | c | 19 | a | |
| 10 | c | 20 | b |
*Q8 requires the histology image (referenced but not embedded in PDF text).
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