you are an proffessional examiner of pathology with 20 years of experience . Write a 20 marks question on acute inflammation.
Here is a professionally crafted 20-mark examination question on acute inflammation, structured as a pathology examiner with 20 years of experience would write it:
PATHOLOGY EXAMINATION
Subject: General Pathology
Total Marks: 20
Time Allowed: 40 minutes
QUESTION
(A) Long Answer [10 Marks]
A 28-year-old male presents to the emergency department with a 2-day history of a painful, swollen, erythematous right index finger following a splinter injury. On examination, the affected area is warm to touch, tender, and shows restricted movement. A small collection of creamy-white pus is visible under the skin.
(i) Name the five cardinal signs of acute inflammation seen in this patient and explain the vascular and cellular events that produce each sign. (5 marks)
(ii) Describe in detail the sequence of cellular events from the onset of injury to the formation of pus, including the roles of neutrophils in phagocytosis and bacterial killing. (5 marks)
(B) Short Notes [6 Marks] — Attempt ANY TWO of the following (3 marks each)
(i) Chemical mediators of acute inflammation - list the major mediators and explain how histamine and bradykinin contribute to increased vascular permeability.
(ii) Differences between exudate and transudate - include the pathophysiological basis, protein content, specific gravity, and two clinical examples of each.
(iii) Morphological types of acute inflammation - describe fibrinous, pseudomembranous, and suppurative inflammation with one clinicopathological example of each.
(C) Structured / Applied Question [4 Marks]
The following lab findings are reported for the patient above:
| Parameter | Value |
|---|---|
| TLC (WBC count) | 18,000/mm³ |
| Differential - Neutrophils | 85% |
| CRP | Elevated |
| ESR | 55 mm/hr |
| Pus culture | Staphylococcus aureus |
(i) What is the term for the elevated neutrophil count seen in bacterial infections, and what cytokines are responsible for stimulating bone marrow to produce this response? (2 marks)
(ii) Explain how S. aureus evades neutrophil killing and what enzymes or toxins it produces that contribute to pus formation and tissue destruction. (2 marks)
MARKING SCHEME / EXAMINERS' NOTES
Section A(i) - 5 Marks
| Cardinal Sign | Mechanism | Marks |
|---|---|---|
| Rubor (redness) | Arteriolar dilatation - increased blood flow (hyperemia) | 1 |
| Calor (heat) | Increased blood flow + metabolic activity | 0.5 |
| Tumor (swelling) | Increased vascular permeability - exudate in interstitium | 1 |
| Dolor (pain) | PGE2, bradykinin acting on nociceptors | 1 |
| Functio laesa (loss of function) | Combined effect of pain + swelling | 0.5 |
| Vascular events: transient vasoconstriction, sustained vasodilatation, increased permeability | 1 |
Section A(ii) - 5 Marks
| Topic | Expected Content | Marks |
|---|---|---|
| Margination, rolling, adhesion (selectins/integrins) | PECAM-1, ICAM-1, E-selectin | 1 |
| Emigration and chemotaxis (IL-8, C5a, LTB4) | 1 | |
| Phagocytosis: opsonization (IgG, C3b), pseudopod formation, phagosome | 1 | |
| Killing: oxidative burst (NADPH oxidase, MPO-H2O2-halide), non-oxidative (lysozyme, defensins) | 1.5 | |
| Pus formation: dead neutrophils + liquefied tissue + bacteria = abscess | 0.5 |
Sections B and C
- Award marks based on accuracy, correct terminology, and clinical correlation.
- Deduct 0.5 marks for factually incorrect statements.
EXAMINER'S COMMENTS
This question tests three cognitive levels:
- Knowledge/Recall - naming cardinal signs, listing mediators
- Understanding/Application - linking vascular events to clinical signs, interpreting lab data
- Analysis/Synthesis - integrating microbiology with pathology in the clinical scenario
Recommended for: MBBS Final Year, MD Pathology entrance, USMLE Step 1 preparation
This question covers vascular events, cellular events, chemical mediators, morphological types, lab interpretation, and microbial pathogenesis - all core domains of acute inflammation as expected in a well-rounded 20-mark examination question.
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