Pathology Paper I – MCQ Answers (Q.1, Items 1-20)

1) C. Coombs test — Spherocytes + jaundice/pallor could be hereditary spherocytosis or autoimmune hemolytic anemia. The Direct Coombs test differentiates immune-mediated spherocytosis from hereditary spherocytosis, making it the key diagnostic test here.

2) D. Pulmonary embolism — Classic DVT presentation (unilateral calf pain, swelling, warmth, positive Homan's sign, engorged superficial veins) in a pregnant patient (hypercoagulable state). The major risk is embolization to the lungs.

3) D. Defect in common pathway — Both PT (extrinsic + common) and APTT (intrinsic + common) are prolonged only when the common pathway (factors X, V, prothrombin, fibrinogen) is affected.

4) C. Distribution and extent of disease — Staging (TNM) reflects anatomic spread/extent of tumor; grading (differentiation, anaplasia, mitotic count) reflects biologic aggressiveness, not staging.

5) C. c-e-b-d-a — Vessel spasm → Formation of platelet plug → Blood coagulation → Clot retraction → Clot dissolution.

6) B. Inhibit platelet aggregation — GP IIb/IIIa inhibitors (e.g., abciximab, tirofiban, eptifibatide) block fibrinogen cross-linking between platelets, preventing aggregation (not adhesion).

7) B. Lipochrome — Perinuclear brown pigment in aging myocardium is lipofuscin ("wear-and-tear pigment"/lipochrome), an autophagic residual body product of lipid peroxidation.

8) B. Dystrophic calcification — Psammoma bodies (laminated calcific concretions) form in areas of necrotic/degenerating tumor tissue despite normal serum calcium — this is dystrophic, not metastatic, calcification.

9) B. Increased serum iron, Decreased TIBC — Hereditary hemochromatosis ("bronze diabetes": skin pigmentation + cirrhosis + diabetes) shows increased serum iron and transferrin saturation with decreased/low-normal TIBC.

10) A. Aflatoxin B1 — Produced by Aspergillus flavus contaminating groundnuts/stored grains; strongly linked to hepatocellular carcinoma (via TP53 mutation, codon 249).

11) B. Beta-pleated sheet tertiary structure — Amyloid's apple-green birefringence under polarized light with Congo red is due to its cross-beta-pleated sheet configuration, regardless of the specific protein subtype.

12) C. ABO(H) antigens are present in most body tissues and fluids — This wide tissue distribution is why ABO compatibility is critical in transfusion and transplantation.

13) D. Triglyceride — Alcoholic hepatic steatosis: clear, empty-appearing cytoplasmic vacuoles on H&E are triglyceride (fat) that dissolves out during processing.

14) B. Decreased oncotic pressure — Cirrhosis → hypoalbuminemia → decreased plasma oncotic pressure, contributing to ascites (along with portal hypertension). The protein value of 2.3 g/dL (transudate-range) fits.

15) C. p53 — p21, p27, and p57 are actual CDK inhibitor proteins (CIP/KIP family). p53 is a tumor-suppressor transcription factor that induces p21 but is not itself a CDK inhibitor.

16) A. Chromosomal disorders — Karyotyping visualizes number/structure of chromosomes to detect aneuploidies and structural rearrangements.

17) B. Sarcoidosis — Classically produces non-caseating granulomas; TB and histoplasmosis typically show caseating (necrotizing) granulomas.

18) B. Extrinsic pathway of apoptosis — CD95 (Fas) is a death receptor; Fas-FasL binding activates caspase-8 via the extrinsic (death receptor) apoptotic pathway.

19) B. Immunoglobulins — Russell bodies are eosinophilic, distended rough ER inclusions in plasma cells packed with accumulated immunoglobulin.

20) A. Medulloblastoma — Psammoma bodies are typical of papillary thyroid carcinoma, meningioma, and papillary serous cystadenocarcinoma of the ovary. Medulloblastoma instead characteristically shows Homer-Wright rosettes, not psammoma bodies.

Note on some answer-key marks visible in your photos: A few options appeared pre-marked/ticked on the paper (e.g., "Reticulocyte count" for Q1, "Pulmonary embolus" for Q2, "Platelet function defect" for Q3, "Metastatic calcification" for Q8, "Decreased serum iron, increased TIBC" for Q9, "Beta-naphthylamine" for Q10). Based on standard pathology teaching (Robbins), several of these marked choices are incorrect for the vignette described - I've given the pathologically correct answer with reasoning above so you can cross-check against your course's specific answer key, since exam answer keys occasionally contain errors.