STEP 1 — MCQs (NO answers here)

MCQ 1 — Basic Definition

An infarct is best defined as:

a. A localized area of hemorrhage

b. An area of ischemic necrosis caused by occlusion of vascular supply

c. An area of inflammatory necrosis

d. A focal edema due to venous obstruction

e. A region of reversible ischemia

MCQ 2 — Clinical Importance

Which statement is TRUE?

a. Infarction is rare and clinically trivial

b. Myocardial and cerebral infarction account for a large proportion of deaths from cardiovascular disease

c. Pulmonary infarction is always fatal

d. Bowel infarction is usually asymptomatic

e. Gangrene is unrelated to infarction

MCQ 3 — Common Sites and Outcomes

Match organ with statement MOST consistent with infarction:

a. Heart

b. Brain

c. Lung

d. Bowel

e. Distal extremities in diabetics

1. Often fatal when infarction occurs
2. Common complication, not always fatal
3. Major cause of overall mortality
4. Often presents as gangrene and morbidity
5. Common cause of stroke

Choose the BEST pair:

a. Heart → 3; Brain → 5; Bowel → 1; Lung → 2; Extremities → 4

b. Heart → 1; Brain → 2; Lung → 3; Bowel → 4; Extremities → 5

c. Heart → 4; Brain → 3; Lung → 2; Bowel → 5; Extremities → 1

d. Heart → 5; Brain → 3; Lung → 1; Bowel → 4; Extremities → 2

e. Lung → 3; Extremities → 1; Brain → 4

MCQ 4 — Main Cause of Infarcts

Most infarcts are caused by:

a. Immune complex deposition

b. Arterial thrombosis or arterial embolism

c. Vasculitis alone

d. Venous thrombosis in organs with many efferent veins

e. Isolated vasospasm without structural disease

MCQ 5 — Other Causes of Arterial Occlusion

Which is NOT listed as a cause of arterial obstruction leading to infarction?

a. Vasospasm

b. Intraplaque hemorrhage expanding an atheroma

c. Extrinsic vessel compression by tumor

d. Compression from edema in tight compartments

e. Hyperglycemia

MCQ 6 — Mechanical Causes of Infarction

Which are examples of mechanical distortion of vessels causing infarction?

a. Testicular torsion and bowel volvulus

b. Hypertension and diabetes

c. Polycythemia and anemia

d. Hyperlipidemia and obesity

e. Iron deficiency and sepsis

MCQ 7 — Venous Thrombosis and Infarction

Which statement about venous thrombosis is MOST accurate?

a. Venous thrombosis usually leads to infarction in most organs

b. Venous thrombosis usually causes congestion, not infarction, due to rapid opening of bypass channels

c. Venous thrombosis never causes congestion

d. Venous thrombosis always produces white infarcts

e. Venous thrombosis always produces hemorrhagic infarcts in all organs

MCQ 8 — Organs Prone to Venous Infarcts

Infarcts due to venous thrombosis most commonly occur in:

a. Organs with multiple efferent veins

b. Organs with a single efferent vein (e.g., testis, ovary)

c. Skeletal muscle only

d. Skin only

e. Brain only

MCQ 9 — Morphologic Classification

Infarcts are classified based on:

a. Color and presence/absence of bacteria

b. Size and patient age

c. Organ only

d. Cause only

e. Location only

MCQ 10 — Red vs White Infarct

Red infarcts are also called:

a. Anemic infarcts

b. Hemorrhagic infarcts

c. Septic infarcts

d. Bland infarcts

e. Liquefactive infarcts

MCQ 11 — Conditions for Red Infarcts

Red (hemorrhagic) infarcts are typically seen in all of the following EXCEPT:

a. Venous occlusion (e.g., ovarian torsion)

b. Loose tissues like lung where blood can collect in infarct zone

c. Tissues with dual circulations (lung, small intestine)

d. Previously congested tissues

e. Solid organs with dense end-arterial circulation and low seepage

MCQ 12 — Conditions for White Infarcts

White (anemic) infarcts are typically seen in:

a. Venous occlusions

b. Loose spongy organs

c. Solid organs with end-arterial circulations like heart, spleen, kidney

d. Lungs and intestines with dual supply

e. Only skin

MCQ 13 — Shape and Orientation

Typical infarct shape and orientation:

a. Round, with vessel at center

b. Wedge-shaped, apex at occluded vessel, base at organ periphery

c. Linear with vessel parallel

d. Irregular with no predictable orientation

e. Always circular subcapsular lesion

MCQ 14 — Surface Changes

When the infarct base is on a serosal surface, there is often:

a. Caseous necrosis

b. Overlying fibrinous exudate

c. Purulent exudate always

d. No change

e. Calcification

MCQ 15 — Color Changes Over Time

In organs without dual circulation and with arterial occlusion, infarcts typically:

a. Become progressively more hemorrhagic

b. Become progressively paler and more sharply defined

c. Disappear completely without scarring

d. Stay indistinct and congested

e. Turn green due to bile pigments

MCQ 16 — Histologic Necrosis Type

In most tissues, the main histologic pattern in infarcts is:

a. Liquefactive necrosis

b. Caseous necrosis

c. Coagulative necrosis

d. Fat necrosis

e. Fibrinoid necrosis

MCQ 17 — Exception to Necrosis Pattern

Which organ is the classic exception where infarction produces liquefactive necrosis?

a. Liver

b. Kidney

c. Lung

d. Brain

e. Spleen

MCQ 18 — Inflammatory Response

The inflammatory response at the margins of infarcts:

a. Is absent

b. Starts after several weeks

c. Begins within a few hours and is well developed in 1–2 days

d. Occurs only if infection is present

e. Occurs only in septic infarcts

MCQ 19 — Ultimate Healing

Most infarcts ultimately:

a. Undergo complete regeneration without scarring

b. Are replaced by scar tissue

c. Turn into granulomas

d. Calcify only

e. Remain as permanent necrotic tissue without change

MCQ 20 — Septic Infarcts

Septic infarcts occur when:

a. There is always a primary venous thrombosis

b. Infected valve vegetations embolize or microbes seed necrotic tissue

c. Only in diabetic patients

d. Only in spleen

e. Only after surgery

MCQ 21 — Outcome of Septic Infarcts

Septic infarcts are typically converted into:

a. Seromas

b. Cysts

c. Abscesses with more intense inflammation and healing by organization and fibrosis

d. Hematomas

e. Fat necrosis

STEP 2 — ANSWERS + SHORT EXPLANATIONS

MCQ 1 — b

Infarct = area of ischemic necrosis due to vascular occlusion.

MCQ 2 — b

Heart and brain infarction are major causes of death in cardiovascular disease.

MCQ 3 — a

Heart → major mortality; brain → stroke; lung → common complication; bowel → often fatal; extremities → gangrene and morbidity.

MCQ 4 — b

Arterial thrombosis or embolism causes the vast majority of infarcts.

MCQ 5 — e

Hyperglycemia is not listed as a direct cause; others (vasospasm, intraplaque hemorrhage, tumor compression, compartment edema) are.

MCQ 6 — a

Testicular torsion and bowel volvulus = twisting → vessel compromise → infarction.

MCQ 7 — b

Venous thrombosis usually → congestion, not infarction, because bypass channels open; infarction only in special cases.

MCQ 8 — b

Venous infarcts → organs with single efferent vein (e.g., testis, ovary).

MCQ 9 — a

Classified by color (red/white) and whether septic vs bland.

MCQ 10 — b

Red infarcts = hemorrhagic infarcts.

MCQ 11 — e

Red infarcts occur with venous occlusion, loose tissues, dual supply, previous congestion, or reperfusion — not classic solid end-arterial organs with limited seepage.

MCQ 12 — c

White infarcts: arterial occlusion in solid, end-arterial organs (heart, spleen, kidney).

MCQ 13 — b

Classically wedge-shaped, apex = occluded vessel, base = organ periphery.

MCQ 14 — b

Serosal base often has overlying fibrinous exudate.

MCQ 15 — b

In such organs, infarcts become progressively paler and sharply demarcated.

MCQ 16 — c

Most infarcts show ischemic coagulative necrosis.

MCQ 17 — d

Brain infarcts → liquefactive necrosis, not coagulative.

MCQ 18 — c

Inflammation starts within hours, well formed by 1–2 days.

MCQ 19 — b

Most infarcts are ultimately replaced by scar (fibrosis).

MCQ 20 — b

Septic infarcts: infected vegetations embolize or microbes seed necrotic tissue.

MCQ 21 — c

They become abscesses with strong inflammation and heal by organization and fibrosis.

STEP 3 — HIGH-YIELD NOTES (EXAM-READY)

1. Definition & Clinical Relevance

• Infarct = area of ischemic necrosis due to occlusion of vascular supply.
• Major clinical impact:
• Heart + brain infarcts → large fraction of cardiovascular deaths.
• Pulmonary infarction → common complication.
• Bowel infarction → often fatal.
• Distal extremity infarction (gangrene) → major morbidity, especially in diabetics.

2. Causes of Infarction

A. Most Common

• Arterial thrombosis
• Arterial embolism

B. Less Common Arterial Causes

• Vasospasm.
• Intraplaque hemorrhage → expansion of atheroma → lumen occlusion.
• Extrinsic compression of vessels:
• Tumor.
• Dissecting aortic aneurysm.
• Edema in confined space (e.g., anterior tibial compartment syndrome).

C. Other Mechanical Causes

• Vessel twisting:
• Testicular torsion.
• Bowel volvulus.
• Traumatic vascular rupture.
• Entrapment of vessels in a hernia sac.

D. Venous Thrombosis

• Usually → congestion, not infarction:
• Collateral/bypass channels often open and maintain enough outflow for arterial inflow.
• Venous infarcts occur when:
• Organ has single efferent vein → e.g., testis, ovary.

3. Morphology – Classification

Infarcts classified by:

1. Color (amount of hemorrhage)
• Red (hemorrhagic)
• White (anemic)
2. Infection status
• Septic (infected)
• Bland (sterile)

4. Red (Hemorrhagic) Infarcts

Seen in:

1. Venous occlusions
• e.g., ovarian torsion.
2. Loose tissues where blood can pool:
• e.g., lung.
3. Dual circulations:
• Lung, small intestine (partial collateral arterial flow).
4. Previously congested tissue:
• Slow venous outflow → high back-pressure.
5. Reperfusion after arterial occlusion:
• e.g., after angioplasty → blood re-enters previously infarcted bed → hemorrhage.

Features:

• Often spongy organs (e.g., lung).
• Extravasated RBCs:
• Phagocytosed by macrophages.
• Heme iron → hemosiderin.
• If extensive → firm brown residue.

5. White (Anemic) Infarcts

Seen in:

• Arterial occlusions in solid organs with end-arterial circulation:
• Heart, spleen, kidney.
• High tissue density → limits seepage of blood from adjacent vascular beds.

Evolution:

• Initially:
• Poorly defined, may be slightly hemorrhagic at margin.
• Over time:
• Become paler.
• Sharply demarcated.
• Edges develop narrow hyperemic rim (inflammation).

6. Gross Shape & Orientation

• Classic infarct:
• Wedge-shaped.
• Apex at site of occluded vessel.
• Base toward organ periphery.
• If base is on a serosal surface:
• Often covered by fibrinous exudate.

7. Microscopic Changes & Healing

A. Necrosis Pattern

• Most tissues:
• Ischemic coagulative necrosis.
• Brain:
• Liquefactive necrosis (exception).

B. Inflammation & Repair

• Margins:
• Inflammation begins within hours.
• Well defined by 1–2 days.
• Repair:
• Starts at preserved margins.
• If stromal framework intact, some parenchymal regeneration may occur.
• Most infarcts → ultimately replaced by scar tissue.

8. Septic vs Bland Infarcts

• Bland infarct:
• Sterile, no infection.
• Septic infarct:
• Occurs when:
• Infected cardiac valve vegetations embolize (e.g., infective endocarditis).
• Microbes seed necrotic tissue.
• Outcome:
• Infarct area → abscess.
• Strong inflammatory response.
• Healing by organization and fibrosis (dense scarring).