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Reading File

Finding Sources

Reading File

Finding Sources

ASSIGNMENT 5 - COMPLETE ANSWERS

C.U. Shah Medical College | Second MBBS | Pathology | 2025

SECTION - I

Q.1 - A 60-year-old man: Proteinuria + 35% Plasma Cells in Bone Marrow + Apple Green Birefringence on Congo Red [10 marks]

1) Probable Diagnosis (1 mark)

Multiple Myeloma with AL (Primary) Amyloidosis

The triad of:

Proteinuria (Bence-Jones protein / nephrotic syndrome from amyloid kidney deposits)
Bone marrow showing 35% plasma cells (>10% confirms Multiple Myeloma)
Tissue biopsy: Congo red stain + apple green birefringence under polarized light = classic Amyloid deposit

This is Primary/AL Amyloidosis arising from the plasma cell dyscrasia of Multiple Myeloma.

2) Definition of Amyloidosis (1 mark)

Amyloidosis is a pathological condition characterized by extracellular deposition of fibrillar proteinaceous material (amyloid) derived from misfolded proteins in various organs and tissues, leading to progressive organ dysfunction. The deposited fibrils have a beta-pleated sheet configuration, which confers resistance to proteolysis and gives apple green birefringence on Congo red staining under polarized light.

3) Classification of Amyloidosis (2 marks)

A. Based on Distribution:

Type	Description
Systemic (Generalized)	Affects multiple organs
Localized	Confined to one organ/tissue

B. Based on Precursor Protein (Biochemical Classification):

Type	Precursor Protein	Associated Condition
AL (Primary)	Immunoglobulin light chains (lambda/kappa)	Multiple Myeloma, Monoclonal Gammopathy
AA (Secondary)	Serum Amyloid A (SAA) protein - liver-derived	Chronic inflammation (TB, RA, Osteomyelitis, Crohn's)
ATTRwt (Senile Systemic)	Wild-type Transthyretin (TTR)	Old age, cardiac amyloidosis (males >70 yrs)
ATTRv (Familial)	Variant/mutant Transthyretin	Familial amyloid polyneuropathy
Aβ2m	β2-microglobulin (MHC class I component)	Long-term hemodialysis
Aβ	Amyloid Precursor Protein (APP)	Alzheimer disease
Localized	Various (e.g., amylin/AIAPP)	Islets of Langerhans in Type 2 DM

4) Pathogenesis of Amyloidosis (3 marks)

Core Mechanism: Protein Misfolding and Aggregation

Step 1 - Increased production of amyloidogenic protein:
- In AL amyloidosis: monoclonal plasma cells in Multiple Myeloma produce excess free immunoglobulin light chains (lambda > kappa)
- In AA amyloidosis: chronic inflammation drives liver to produce excess SAA protein (acute-phase reactant)
Step 2 - Protein misfolding:
- Normally, misfolded proteins are degraded intracellularly via proteasomes or extracellularly by macrophages
- In amyloidosis, these quality-control mechanisms fail
- The proteins misfold into a beta-pleated sheet conformation
Step 3 - Fibrillogenesis:
- Misfolded monomers aggregate to form oligomers, then protofibrils, then mature amyloid fibrils
- Seeding effect: once fibrils form, they act as templates (seeds) for further fibril growth, accelerating deposition
Step 4 - Extracellular deposition:
- Fibrils deposit in extracellular spaces, often along basement membranes
- Associated proteins: Serum Amyloid P (SAP) component, Apolipoprotein E, heparan sulfate proteoglycans - these stabilize fibrils and protect against degradation
Step 5 - Organ damage:
- Mechanical disruption of tissue architecture
- Some amyloidogenic proteins activate signaling pathways that increase ROS production and impair mitochondrial function
- Result: progressive organ dysfunction (nephrotic syndrome, cardiomyopathy, hepatomegaly, neuropathy)

Diagram:

Plasma Cells (Multiple Myeloma)
        ↓ Excess light chains
Protein Misfolding → Beta-pleated sheet configuration
        ↓
Fibril Formation (seeded polymerization)
        ↓
Extracellular Deposition in tissues
        ↓
Congo red (+) → Apple green birefringence (polarized light)

5) Morphology of Amyloidosis in Different Tissues - Any TWO (3 marks)

A. KIDNEY (most commonly affected in AL and AA amyloidosis):

Gross: Kidneys are enlarged, pale, waxy, "large white kidney." In advanced disease, contracted kidneys may be seen.
Microscopy (H&E): Amorphous, eosinophilic, hyaline material deposits in:
- Mesangium of glomeruli (earliest and most prominent)
- Along glomerular capillary walls (GBM)
- Interstitium and tubular basement membranes
- Walls of arterioles
Congo red stain: Pink-red color; apple green birefringence under polarized light
Consequence: Proteinuria → Nephrotic syndrome → Renal failure

B. SPLEEN: Two patterns:

Sago spleen: Amyloid deposits in the lymphoid follicles (white pulp) → appear as small, grayish, translucent nodules resembling sago grains (tapioca-like appearance)
Lardaceous (Bacon) spleen: Diffuse deposits in the splenic sinusoids/red pulp → large, firm, waxy spleen with a "lard-like" appearance on cut section
Both patterns: Congo red positive, apple green birefringence

C. LIVER (for reference):

Gross: Enlarged, firm, pale, waxy liver ("lardaceous liver")
Microscopy: Amyloid deposits in Space of Disse (between hepatocytes and sinusoidal endothelium), eventually compressing hepatocytes
Hepatomegaly + mild liver dysfunction; rarely liver failure

Q.2 - Short Notes - ANY THREE (3×5 = 15 marks)

Q.2.1 - Define Metastasis; Describe Mechanism and Biology of Invasion and Metastasis (1+4)

Definition: Metastasis is the spread of malignant tumor cells from the primary site to distant, non-contiguous tissues/organs to form secondary tumor deposits. It is the hallmark of malignancy and the most common cause of cancer-related mortality.

Biology and Mechanism of Invasion and Metastasis (The Metastatic Cascade):

Step 1 - Local Invasion:

Malignant cells lose cell-cell adhesion (downregulation of E-cadherin) and cell-ECM adhesion
Tumor cells secrete matrix metalloproteinases (MMPs) - especially MMP-2 and MMP-9 - and serine proteases that degrade basement membrane and ECM
Epithelial-Mesenchymal Transition (EMT): tumor cells acquire a mesenchymal phenotype - fibroblast-like, motile, invasive
- Key transcription factors: Snail, Twist, ZEB1 - suppress E-cadherin, upregulate vimentin
Actin cytoskeleton remodeling drives formation of lamellipodia and invadopodia for directional migration

Step 2 - Intravasation:

Tumor cells penetrate blood vessels or lymphatics (lymphatics easier to invade)
Vascular permeability is increased by tumor-secreted VEGF
Most intravasated cells are killed by immune surveillance (NK cells, cytotoxic T cells)

Step 3 - Survival in Circulation:

Circulating Tumor Cells (CTCs) are vulnerable to shear forces, anoikis, and immune attack
Tumor cells may travel as clusters (homo-aggregates) or associate with platelets for protection

Step 4 - Arrest and Extravasation:

Cells arrest at distant capillary beds, often due to size or specific receptor-ligand interactions
Organ tropism (seed and soil hypothesis - Paget, 1889):
- "Seed" = tumor cell
- "Soil" = favorable organ microenvironment
- E.g., breast cancer → bone (via CXCR4-CXCL12 axis), prostate → bone, colon → liver

Step 5 - Formation of Metastatic Colony:

Extravasated cells must adapt to new microenvironment
Some enter dormancy (micrometastasis); others proliferate
Neo-angiogenesis required for growth beyond 1-2 mm

Routes of Metastasis:

Route	Common Cancers
Lymphatic	Carcinomas (breast, colon, lung) - to regional lymph nodes
Hematogenous	Sarcomas, also carcinomas - liver, lungs, bone, brain
Transcoelomic	Ovarian, colonic - peritoneal spread
Perineural	Prostate, pancreatic
Direct (implantation)	Surgical seeding

Q.2.2 - Describe Morphological Forms of Reversible Cell Injury

Definition: Reversible cell injury = derangement of function and morphology that cells can recover from if the damaging stimulus is removed.

Two Main Morphological Patterns:

A. Cellular Swelling (Hydropic Change / Vacuolar Degeneration):

Most common and earliest sign of cell injury
Mechanism: Failure of Na+/K+ ATPase pump (due to ATP depletion, toxins, hypoxia) → Na+ and water accumulate intracellularly → cell swelling
Gross: Organ appears enlarged, pale, with increased weight
LM (Light Microscopy):
- Cells are enlarged
- Cytoplasm shows small, clear vacuoles (pinched-off segments of ER) - "vacuolar degeneration"
- Nucleus is normal or slightly enlarged
EM (Electron Microscopy):
- Plasma membrane blebbing (blebs/bullae)
- ER swelling and ribosome detachment
- Mitochondria swelling with small densities
- Nuclear chromatin clumping

B. Fatty Change (Steatosis):

Intracellular accumulation of neutral lipid (triglycerides) in non-adipose cells
Most commonly seen in: Liver (most important), heart, kidney
Causes: Alcoholism, protein malnutrition, diabetes, hypoxia, toxins (CCl4)
Mechanism in liver:
- Excess FFAs delivered to liver
- Increased fatty acid synthesis
- Decreased beta-oxidation
- Decreased apoprotein synthesis (↓ VLDL export) → All lead to triglyceride accumulation
Gross (Liver): Enlarged, yellow ("yellow liver"), greasy, soft
LM: Hepatocytes contain clear vacuoles of variable size
- Microvesicular steatosis: Multiple small droplets, nucleus central (e.g., acute fatty liver of pregnancy)
- Macrovesicular steatosis: Large single vacuole pushes nucleus to periphery (e.g., alcoholic liver disease)
Special stains: Oil Red O (frozen sections) = red; Sudan IV = red

Reversibility criteria: If stimulus removed before membrane damage becomes irreversible, cells recover. Key point of no return = massive calcium influx + outer mitochondrial membrane permeabilization.

Q.2.3 - Wound Healing (Burn case: A 39-year-old man, large surface burn - heals in 3 weeks without surgery)

This scenario describes healing by secondary intention (large wound) ultimately achieving complete healing - a superficial enough burn (partial thickness) allowing re-epithelialization.

A. Sequence of Wound Healing in Above Scenario (3 marks):

Phase 1 - Hemostasis and Inflammation (Day 0-3):

Blood clot (fibrin + platelets) forms immediately
Platelets release: PDGF, TGF-β, TGF-α, EGF → initiate healing
Vasoconstriction (minutes) → vasodilation → increased permeability
Day 1-2: Neutrophils infiltrate (clean debris, bacteria)
Day 2-3: Macrophages arrive and dominate - most important cells for wound healing
- Release: IL-1, TNF, FGF, VEGF, TGF-β, PDGF
- Phagocytose debris and apoptotic neutrophils

Phase 2 - Proliferation / Granulation Tissue (Day 3-5 to 3 weeks):

Angiogenesis: New capillary sprouts form (VEGF, FGF-2 driven)
Fibroplasia: Fibroblasts proliferate and migrate in
- Produce collagen (initially type III, immature)
- Produce fibronectin, proteoglycans
Granulation tissue = new blood vessels (pink) + loose ECM + macrophages, fibroblasts
- Hallmark: "granular" pink appearance
Myofibroblasts (derived from fibroblasts): contract wound edges - wound contraction
Re-epithelialization: Keratinocytes from wound edges and adnexal structures (hair follicles, sweat glands) migrate across the wound surface
- In partial-thickness burns: adnexal structures preserved → complete re-epithelialization possible without skin grafts (explains 3-week healing without surgery)

Phase 3 - Remodeling / Scar Maturation (Week 3 - months/years):

Type III collagen replaced by type I (stronger, more organized)
Cross-linking of collagen fibers increases tensile strength
Collagenases (MMPs) and their inhibitors (TIMPs) balance matrix remodeling
Vascularity decreases → scar becomes pale
Maximum tensile strength: ~70-80% of normal skin (never 100%)

B. Complications of Wound Healing (2 marks):

Complication	Description
Infection	Most common; delays healing, promotes excessive inflammation
Wound dehiscence	Reopening of wound, especially abdominal; due to increased intra-abdominal pressure or poor nutrition
Incisional hernia	Defect in abdominal wall after dehiscence
Hypertrophic scar	Raised, red scar confined to wound margins; excessive collagen deposition; may regress
Keloid	Scar extends beyond wound margins (claw-like); does not regress; more common in dark-skinned individuals; more collagen type I and III, excess TGF-β
Contracture	Excessive myofibroblast activity; especially in burns; can restrict movement across joints
Deficient scar (Ulceration)	Inadequate granulation, poor vascularization (diabetes, venous stasis)
Desmoid tumor	Rare; fibromatosis arising in scar
Wound sinus/fistula	Persistent tract due to infection, foreign body

Q.2.4 - Enumerate Blood Components in Blood Bank; Advantages and Disadvantages of Fresh Frozen Plasma (1+4)

Blood Components Available in Blood Bank:

Packed Red Blood Cells (pRBCs)
Fresh Frozen Plasma (FFP)
Platelet Concentrate (Random Donor Platelets / Single Donor Apheresis Platelets)
Cryoprecipitate
Cryopoor plasma (Cryosupernatant)
Granulocyte concentrate
Albumin (4% and 20%)
Immunoglobulins (IVIG)
Factor concentrates (Factor VIII, IX, etc.)
Whole blood (rarely used)

Fresh Frozen Plasma (FFP):

Prepared from whole blood by centrifugation within 6-8 hours of collection and frozen at -18°C or below
Contains all coagulation factors (I, II, V, VII, VIII, IX, X, XI), fibrinogen, protein C, protein S, antithrombin
Volume: ~200-250 mL per unit; stored up to 12 months at -30°C

ADVANTAGES	DISADVANTAGES
Contains ALL coagulation factors including labile factors V and VIII	Risk of transfusion-transmitted infections (HIV, HBV, HCV, syphilis)
Used in multiple coagulation factor deficiencies (DIC, liver disease, massive transfusion)	Risk of transfusion-related reactions: TRALI (Transfusion-Related Acute Lung Injury) - most serious
Immediate reversal of warfarin anticoagulation	TACO (Transfusion-Associated Circulatory Overload) - especially in elderly/cardiac patients
Source of plasma proteins (fibronectin, complement)	Requires ABO compatibility (not group-specific in emergency but ideally matched)
Available in most blood banks	Requires thawing (30-37°C, 20-30 min) - not instantly available
Can be used for plasmapheresis (TTP treatment)	Large volume needed (15 mL/kg) to achieve hemostasis
Used in coagulopathies of liver disease	Febrile non-hemolytic reactions possible
No cross-match required (only ABO typing needed)	Alloimmunization possible
	Short shelf life after thawing (use within 24 hours at 4°C)
	Contains citrate → hypocalcemia with massive transfusion

Q.3 - Short Notes - ANY THREE (3×5 = 15 marks)

Q.3.1 - Enlist Tumour Suppressor Genes; Role of P53 in Tumorigenesis (1+4)

Tumour Suppressor Genes (Anti-oncogenes):

Genes that normally restrain cell growth; loss of function (both alleles = Knudson's two-hit hypothesis) leads to uncontrolled proliferation.

Major Tumour Suppressor Genes:

Gene	Chromosome	Associated Tumor
RB1 (Retinoblastoma)	13q14	Retinoblastoma, Osteosarcoma
TP53	17p13	Most human cancers (>50%)
BRCA1	17q	Breast, Ovarian carcinoma
BRCA2	13q	Breast, Ovarian, Pancreatic
APC	5q21	Colorectal carcinoma (FAP)
NF1	17q	Neurofibromatosis type 1
NF2	22q	Neurofibromatosis type 2
VHL	3p25	Renal Cell Carcinoma
WT1	11p13	Wilms tumor
PTEN	10q23	Breast, Prostate, Endometrial
CDKN2A (p16)	9p21	Melanoma, Pancreatic
SMAD2/SMAD4	18q	Colorectal, Pancreatic

Role of P53 in Tumorigenesis ("Guardian of the Genome"):

Normal P53 Functions:

P53 is a transcription factor (393 aa), encoded by TP53 gene on chromosome 17p13
Normally kept at low levels by MDM2 (an E3 ubiquitin ligase that tags p53 for proteasomal degradation)

Activation of P53: When cells suffer DNA damage, oncogene activation, hypoxia, or telomere shortening:

ATM/ATR kinases are activated
They phosphorylate P53 → P53 released from MDM2 → P53 accumulates
P53 tetramerizes and acts as transcription factor

P53 Downstream Responses - The 4 Key Functions:

DNA Damage
    ↓
P53 Activation
    ↓
┌───────────────────────────────────────────────────┐
│ 1. Cell Cycle Arrest      │ 2. DNA Repair          │
│    (via p21 → inhibits    │    (GADD45, DDB2)      │
│    CDK4/6-Cyclin D)       │                        │
├───────────────────────────┼────────────────────────┤
│ 3. Apoptosis              │ 4. Senescence          │
│    (via BAX, PUMA, NOXA;  │    (permanent growth   │
│    downregulates BCL-2)   │    arrest)             │
└───────────────────────────────────────────────────┘

P53 in Tumorigenesis:

Mutation: >50% of all human cancers have TP53 mutations; mostly missense mutations (gain-of-function) in the DNA-binding domain
Without P53: DNA-damaged cells bypass arrest → continue dividing → accumulate further mutations → malignant transformation
MDM2 amplification: In some tumors (especially sarcomas), MDM2 is overexpressed → degrades p53 without mutation
HPV: E6 protein of high-risk HPV binds p53 and promotes its degradation (mechanism in cervical cancer)
Li-Fraumeni Syndrome: Germline TP53 mutation → multiple cancers at young age (breast, sarcomas, brain tumors, leukemia)

Q.3.2 - 65-year-old Female: Black Discoloration of Foot and Lower Leg, Limb Pulsations Not Palpable, Sharp Line of Demarcation

A) Most Probable Diagnosis (1 mark):

Dry Gangrene (likely due to Peripheral Arterial Disease / Atherosclerosis)

The clinical features - black discoloration, absent pulsations, sharp line of demarcation - point to dry gangrene from arterial occlusion.

B) Etiological Factors (2 marks):

Primary Cause: Atherosclerosis of peripheral arteries (chronic progressive arterial insufficiency)

Risk Factors:

Factor	Details
Diabetes Mellitus	Most important cause of peripheral vascular disease and gangrene in elderly females; accelerates atherosclerosis + microangiopathy + neuropathy
Hypertension	Accelerates atherosclerosis
Smoking	Vasoconstriction + endothelial damage + accelerated atherosclerosis
Hyperlipidemia	Foam cell formation, plaque build-up
Buerger's disease	(Thromboangiitis Obliterans) - though more in young male smokers
Arterial thrombosis/embolism	Acute on chronic arterial occlusion
Raynaud's disease	Less likely here
Old age	Vessel calcification, reduced elasticity

C) Pathogenesis of Dry Gangrene (2 marks):

Arterial occlusion (atherosclerotic plaque ± superimposed thrombosis) → severe ischemia
Ischemia > repair capacity → cells undergo coagulative necrosis
Dehydration/desiccation of tissues: slow arterial occlusion allows time for:
- Venous drainage to remain intact (initially)
- Fluid drains out → tissues become dry, shrunken, mummified
Coagulative necrosis predominates:
- Proteins coagulate
- Tissue becomes firm, hard, blackened (due to iron sulfide from hemoglobin breakdown - FeS)
Sharp line of demarcation:
- Inflammatory reaction between viable and necrotic tissue
- Hyperemia of living tissue vs. black necrotic tissue
No infection (or minimal): dry, avascular tissue is unfavorable for bacterial growth
If infection supervenes → Dry gangrene converts to Wet gangrene

Q.3.3 - Enumerate and Describe Chemical Mediators in Acute Inflammation (1+4)

Classification of Chemical Mediators:

A. Cell-Derived Mediators:

Mediator	Source	Main Actions
Histamine	Mast cells, basophils, platelets	Early vasodilation, increased vascular permeability, bronchoconstriction
Serotonin	Platelets	Vasodilation, increased permeability
Prostaglandins (PGI2, PGE2, PGD2)	Arachidonic acid (COX pathway) from mast cells, macrophages	Vasodilation, pain (sensitize nociceptors), fever (PGE2 acts on hypothalamus)
Leukotrienes (LTC4, LTD4, LTE4 = slow-reacting substances; LTB4)	Arachidonic acid (LOX pathway)	LTB4: potent chemotaxis for neutrophils; LTC4/D4/E4: bronchoconstriction, mucus secretion, increased permeability
PAF (Platelet Activating Factor)	Mast cells, basophils, neutrophils, endothelium	Platelet aggregation, bronchoconstriction, vasodilation, chemotaxis
Reactive Oxygen Species (ROS)	Neutrophils, macrophages (NADPH oxidase)	Bacterial killing, tissue damage, PMN recruitment
Nitric Oxide (NO)	Endothelium (eNOS), macrophages (iNOS)	Vasodilation, bactericidal, reduces platelet aggregation
Lysosomal enzymes	Neutrophils, macrophages	Tissue destruction, killing of microbes
Cytokines: IL-1, TNF-α	Macrophages	Fever, acute-phase response, leukocyte activation, ICAM/VCAM expression
IL-8 (CXCL8)	Macrophages, endothelium	Potent neutrophil chemotaxis

B. Plasma-Derived Mediators:

System	Mediators	Actions
Complement System	C3a, C5a (anaphylatoxins); C5b-9 (MAC); C3b (opsonin)	C3a/C5a: mast cell degranulation, chemotaxis; MAC: cell lysis
Kinin System	Bradykinin	Pain, vasodilation, increased permeability
Coagulation System	Thrombin, fibrin split products, Factor Xa	Platelet aggregation, fibrin formation
Fibrinolytic System	Plasmin	Complement activation, fibrin cleavage

Key Points:

Vasodilation: Histamine, NO, PGI2, PGE2, bradykinin
Increased Permeability: Histamine, C3a/C5a, LTC4/D4, bradykinin, substance P
Chemotaxis: LTB4, C5a, IL-8, bacterial products (fMLP)
Fever: IL-1, TNF-α, IL-6 (endogenous pyrogens) → induce COX-2 in hypothalamus → PGE2 → raises temperature set point

Q.3.4 - Define Embolism; Types of Embolism; Fat Embolism in Brief (1+1+3)

Definition of Embolism: Embolism is the process of partial or complete obstruction of a blood vessel by a mass (embolus) that has been carried there by the bloodstream. The embolus is a detached intravascular solid, liquid, or gaseous mass that travels from its site of origin to a distant site.

Types of Embolism:

Thromboembolism (most common - 99%)
- Pulmonary thromboembolism (from DVT)
- Systemic arterial embolism (from left heart mural thrombus, vegetations)
Fat embolism
Air/Gas embolism
Amniotic fluid embolism
Tumor embolism (neoplastic cells)
Bone marrow embolism
Foreign body embolism (catheter fragments, talc in IV drug users)
Septic embolism (infected thrombus)
Nitrogen gas embolism (decompression sickness / caisson disease / bends)
Paradoxical embolism (venous embolus crosses to arterial via ASD/VSD)

Fat Embolism:

Definition: Occlusion of blood vessels by fat globules in the circulation.

Causes:

Long bone fractures (femur, tibia) - most common - marrow fat released
Severe burns, crush injuries, pancreatitis
Liposuction, orthopedic surgery
Sickle cell disease (bone marrow necrosis)

Pathogenesis (Two theories):

Mechanical theory: Fat globules from marrow of fractured long bones directly enter torn venules → travel to pulmonary capillaries → obstruct them
Biochemical theory: Stress-induced catecholamines mobilize free fatty acids from adipose tissue → coalesce into fat globules → also toxic injury to pneumocytes and endothelium

Fat Embolism Syndrome (FES):

Develops 1-3 days after injury
Classic triad:
1. Respiratory: Dyspnea, hypoxemia, ARDS-like picture (fat in pulmonary capillaries)
2. Neurological: Confusion, stupor, coma ("shower embolization" to cerebral vessels)
3. Petechiae: Especially on upper chest, conjunctiva, axilla (fat globules in dermal capillaries)
Lab: Fat globules in urine (lipiduria), thrombocytopenia, anemia
CXR: "Snowstorm" pattern
Treatment: Supportive; oxygen, steroids (controversial); prophylaxis with early fracture fixation

Q.4 - Short Notes - ANY FIVE (2×5 = 10 marks)

Q.4.1 - Difference Between Red Infarct and White Infarct

Feature	Red (Hemorrhagic) Infarct	White (Pale/Anemic) Infarct
Blood flow	Dual blood supply or venous occlusion	End-arterial (single) blood supply
Typical organs	Lung, intestine, ovary, testis, brain	Heart (myocardium), spleen, kidney
Mechanism	Re-perfusion of necrotic tissue; collateral vessels allow blood seepage into necrotic area	No collaterals; blood supply completely cut off; no seepage
Appearance (Gross)	Red, hemorrhagic, soft, spongy	Pale/white/yellow, firm, wedge-shaped
Shape	May be irregular	Typically wedge-shaped with base on surface
Border	Hyperemic rim present	Hyperemic rim / hemorrhagic zone around pale center
Consistency	Soft initially	Firm (coagulative necrosis)
Common cause	Venous thrombosis (intestine/ovary); pulmonary embolism with congestion	Arterial thrombosis/embolism
Microscopy	Coagulative necrosis + flooded with RBCs	Coagulative necrosis (shadow outline of cells, no RBCs)
Example	Pulmonary infarct after PE, hemorrhagic cerebral infarct	MI, splenic infarct, renal infarct

Q.4.2 - Contribution of Rudolf Virchow in Field of Pathology

Rudolf Virchow (1821-1902) - "Father of Modern Pathology" / "Pope of Medicine"

Cellular Pathology (1858): Published "Cellularpathologie" - established that all disease arises from pathological changes in cells ("Omnis cellula e cellula" - every cell from a pre-existing cell). Replaced humoral theory.
Virchow's Triad (1856): Identified three factors predisposing to thrombosis:
- Endothelial injury
- Abnormal blood flow (stasis/turbulence)
- Hypercoagulability (blood constituents) Still forms the basis of thrombosis understanding.
Leukemia: First described and named leukemia (1845) - observed "white blood" in two patients.
Embolism and Thrombosis: Distinguished between thrombus and embolus; coined the term "embolism."
Virchow's Node (Troisier's sign): Left supraclavicular lymph node enlargement in gastric/abdominal cancer - bears his name.
Gliosis: Described reactive gliosis in the nervous system.
Amyloid: Coined the term "amyloid" (1854) - thought the deposits were starch-like (amylose = starch) due to iodine staining.
Fibrin: Described fibrinous exudates and their organization.
Anthropology/Public Health: Pioneered social medicine, emphasized the role of social conditions in disease; improved Berlin's public health infrastructure.
Described many entities: Virchow-Robin spaces (perivascular spaces in brain), chromatin, chordoma, etc.

Q.4.3 - Enumerate Cardinal Signs of Acute Inflammation

The cardinal signs were classically described by Celsus (4 signs) and later Virchow added the 5th:

#	Latin	English	Mechanism
1	Rubor	Redness	Vasodilation → increased blood in area → erythema
2	Calor	Heat	Vasodilation → increased warm arterial blood to periphery
3	Tumor	Swelling	Increased vascular permeability → exudate in tissue = edema
4	Dolor	Pain	Sensitization of nociceptors by bradykinin, prostaglandins (PGE2), serotonin
5	Functio laesa	Loss of function	Added by Virchow; result of pain + swelling + tissue damage

Mediators responsible:

Rubor + Calor: Histamine, NO, PGI2, PGE2 (vasodilation)
Tumor: Histamine, C3a/C5a, bradykinin (increased permeability)
Dolor: Bradykinin (direct), PGE2/PGI2 (sensitize C-fibers), substance P

Q.4.4 - Define Paraneoplastic Syndrome; Two Examples

Definition: Paraneoplastic syndromes are symptom complexes in cancer-bearing patients that cannot be explained by local invasion, metastasis, or metabolic effects of the tumor itself (e.g., obstruction, nutrition depletion). They are caused by:

Ectopic secretion of hormones or hormone-like substances by tumor
Immune-mediated cross-reactions (antibodies/T cells against tumor antigens that also target normal tissues)

Significance:

May be the first sign of an occult neoplasm
Can mimic metastasis
May cause significant morbidity
Do not reflect prognosis but indicate presence of cancer

Two Examples:

1. Hypercalcemia of Malignancy (Humoral Hypercalcemia of Malignancy - HHM):

Tumor: Squamous cell carcinoma of lung, Breast cancer, Renal cell carcinoma, Multiple myeloma
Mechanism: Tumor secretes PTHrP (PTH-related Protein) → mimics PTH → increases bone resorption, renal calcium reabsorption → hypercalcemia
Symptoms: Weakness, confusion, polyuria, constipation, bone pain

2. SIADH (Syndrome of Inappropriate ADH secretion):

Tumor: Small cell carcinoma of lung (most common)
Mechanism: Tumor ectopically secretes ADH (vasopressin) → excess water reabsorption → dilutional hyponatremia
Symptoms: Confusion, seizures, lethargy (hyponatremia)

Other examples for knowledge:

Cushing syndrome: Ectopic ACTH secretion (small cell lung cancer)
Eaton-Lambert syndrome: Antibodies against voltage-gated Ca2+ channels (small cell lung cancer) → proximal muscle weakness
Cerebellar degeneration: Anti-Yo antibodies (ovarian/breast cancer)
Acanthosis nigricans: Gastric cancer
DVT (Trousseau syndrome): Mucin-secreting carcinomas (pancreas, GI)

Q.4.5 - Name Various Blood Group Systems; Brief about Bombay Blood Group

Major Blood Group Systems:

System	Gene/Chromosomal Basis	Antigens
ABO	Chromosome 9; glycosyltransferases	A, B, H antigens on RBC
Rh (Rhesus)	Chromosome 1; RHD/RHCE genes	D, C, c, E, e antigens; D most important
Kell	Chromosome 7; KEL gene	K (Kell), k (Cellano) - highly immunogenic
Duffy	Chromosome 1; DARC gene	Fy^a, Fy^b
Kidd	Chromosome 18; SLC14A1 gene	Jk^a, Jk^b
Lewis	Chromosome 19; FUT3 gene	Le^a, Le^b
MNS	Chromosome 4; GYPA/GYPB	M, N, S, s
P	Chromosome 22	P1, P2, p
Lutheran	Chromosome 19	Lu^a, Lu^b
I/i	Chromosome 6; GCNT2	I, i
HLA	Chromosome 6	HLA antigens (on WBCs/platelets primarily)
Bombay (Oh)	FUT1 gene mutation	Absent H antigen

Bombay Blood Group (Oh / hh phenotype):

Discovered: 1952 in Bombay (Mumbai) by Bhende et al.
Incidence: Extremely rare - 1 in 10,000 in India; 1 in 1,000,000 in Europe
Genetics: Homozygous mutations in FUT1 gene (H gene) on chromosome 19
- Normally FUT1 encodes H-transferase enzyme that adds fucose to form H antigen on RBC surface
- H antigen is the precursor for A and B antigens
- In Bombay phenotype: no H antigen formed → no A or B antigens formed either

Key Features:

Feature	Bombay Blood Group
Antigens on RBC	None (no H, A, or B)
Antibodies in serum	Anti-H, Anti-A, Anti-B (all IgM, naturally occurring)
Compatible blood	Only other Bombay (Oh) blood
ABO typing	Appears as group O (false grouping)
Cross-match	Incompatible with ALL ABO groups including O
Transfusion significance	Can receive only Bombay blood; any other blood causes severe hemolytic reaction
Secretor status	Always non-secretors for H
Inheritance	Autosomal recessive

Clinical significance:

Bombay individuals appear to be group O on forward typing but anti-H reaction reveals true identity
Pre-operative planning: store autologous blood or identify Bombay donors
Anti-H causes severe, potentially fatal intravascular hemolytic transfusion reaction

Q.4.6 - What is Pyroptosis? Two Differences Between Pyroptosis and Apoptosis

Pyroptosis:

Pyroptosis (from Greek: pyro = fire/fever; ptosis = falling) is a form of programmed, inflammatory cell death characterized by:

Activation of inflammasomes (intracellular protein complexes)
Activation of Caspase-1 (and Caspase-4/5 in humans) and Caspase-11 (in mice)
Cleavage of Gasdermin D (GSDMD) → N-terminal fragment inserts into plasma membrane → forms pores
Cell swelling, osmotic lysis, plasma membrane rupture
Release of IL-1β, IL-18 (pro-inflammatory cytokines) and DAMPs (HMGB1)
Morphologically: cell swelling (not shrinkage), plasma membrane disruption, nuclear damage

Mechanism:

Pathogen / PAMPs / DAMPs
        ↓
Inflammasome Assembly (NLRP3, AIM2, NLRC4)
        ↓
Caspase-1 Activation
        ↓
1. Cleavage of Gasdermin D → Pore formation → Cell lysis + cytokine release
2. Cleavage of pro-IL-1β → mature IL-1β (released through pores)
3. Cleavage of pro-IL-18 → mature IL-18

Two Differences Between Pyroptosis and Apoptosis:

Feature	Pyroptosis	Apoptosis
Inflammatory nature	PRO-INFLAMMATORY; releases IL-1β, IL-18, DAMPs; causes inflammation	NON-INFLAMMATORY (silent cell death); contents packaged into apoptotic bodies; phagocytosed without inflammation
Membrane integrity	Plasma membrane DISRUPTED early (gasdermin pores → cell lysis); cellular contents released	Plasma membrane remains INTACT; cells shrink (not swell); apoptotic bodies formed; no contents spilled
Key caspases	Caspase-1, 4, 5, 11 (inflammatory caspases) + Gasdermin D cleavage	Caspase-3, 7 (executioner); Caspase-8/9 (initiators); no gasdermin
Morphology	Cell swelling, pore formation, osmotic lysis	Cell shrinkage, chromatin condensation, nuclear fragmentation, apoptotic bodies
Physiological role	Defense against intracellular pathogens (bacteria, viruses)	Normal tissue homeostasis, development, removal of autoreactive lymphocytes

SECTION - II

(Note: Section II is partially visible in the image. Based on visible text:)

Q.5 (partially visible): Patient presented with easy fatigability, loss of appetite, pallor. Hemoglobin (Hb) mentioned as (CH)- 20. [This appears to be a hematology/anemia case]

Probable Diagnosis: Based on "easy fatigability, loss of appetite, pallor" + low Hb in a likely female patient = Iron Deficiency Anemia (most common), or could be Anemia of Chronic Disease or Megaloblastic Anemia depending on complete data (MCV, peripheral smear).

Q. (15 marks - partially visible): Disease (likely asking about a specific disease with 2.5+2.5 marks sub-question)

Q. - 25-Year-old Male: Headache, Convulsion; CSF Analysis Shows Plenty of Neutrophils:

A) Most Probable Diagnosis: Acute Bacterial (Pyogenic) Meningitis

CSF findings: Plenty of neutrophils (pleocytosis - PMN dominant) = hallmark of bacterial meningitis
Headache + Convulsions = features of meningeal irritation + raised ICP

Differential by Age (25-year-old):

Neisseria meningitidis (most common in young adults)
Streptococcus pneumoniae
Listeria monocytogenes (immunocompromised)

Complete CSF Findings in Bacterial Meningitis:

Parameter	Normal	Bacterial Meningitis
Appearance	Clear	Turbid/Purulent
Pressure	70-180 mmH2O	Elevated
WBC	<5 lymphocytes	100-10,000+ neutrophils
Protein	15-45 mg/dL	Elevated (>100 mg/dL)
Glucose	50-80 mg/dL	Low (<40 or <2/3 serum)
Gram stain	Negative	Positive (60-90%)

Pathology:

Leptomeninges (pia + arachnoid) show acute inflammation
Subarachnoid space filled with neutrophilic exudate
Vascular congestion, cerebral edema
Gross: "pus over the brain surface"
Complications: hydrocephalus, cerebral abscess, subdural empyema, septicemia, DIC

Robbins, Cotran & Kumar Pathologic Basis of Disease and Robbins & Kumar Basic Pathology were the primary textbook references used throughout these answers.

Note: All answers above are based on standard Second MBBS Pathology curriculum. Key diagrams mentioned should be drawn neatly in the answer sheet for full marks. Write each section answer in appropriate subheadings for maximum score.

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