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NEOPLASIA - Complete MUHS Exam Notes

Based on Robbins & Kumar Basic Pathology | Harsh Mohan | Robbins Pathology

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PART 1: NEOPLASIA - Definition, Classification

Definition (learn this by heart)

Neoplasia = "New growth." A neoplasm is a mass of cells showing uncontrolled, purposeless proliferation that is autonomous - it persists even after the stimulus causing it is removed.

• Oncology = study of tumors (oncos = tumor)
• All neoplasms consist of: (1) parenchyma (proliferating neoplastic cells) + (2) stroma (supporting connective tissue + blood vessels)

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Classification of Neoplasms

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PART 2: TERATOMA

• Arise from totipotent germ cells (gonads - testis/ovary, or extragonadal - mediastinum, retroperitoneum, sacrococcygeal region)
• Contain tissues from all 3 germ layers (ecto, meso, endoderm) in a disorganized arrangement
• Mature (benign) teratoma: Dermoid cyst of ovary - most common. Contains skin, hair, teeth, sebaceous glands
• Immature (malignant) teratoma: Contains immature fetal-type tissues (neuroepithelium). More common in males. AFP elevated
• Exam tip: Benign teratoma = mature (differentiated); Malignant teratoma = immature (poorly differentiated, AFP +ve)

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PART 3: PRECANCEROUS LESIONS (Premalignant Lesions)

A. Precancerous Conditions (Acquired)

B. Precancerous Epithelial Changes (Histological)

• Dysplasia: Loss of uniformity + architectural disorientation of epithelial cells. Cells show variation in size, shape; increased N:C ratio; nuclear hyperchromatism; abnormal mitoses
• Carcinoma in situ (CIS): Full-thickness epithelial dysplasia with intact basement membrane. This is the final premalignant stage
• Progression: Normal → Hyperplasia → Dysplasia (mild → moderate → severe) → CIS → Invasive carcinoma

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PART 4: ANAPLASTIC TUMOR CELLS - MORPHOLOGY

Morphological Features of Anaplastic Cells (H&E - Easy to draw):

ANAPLASTIC CELL - KEY FEATURES:

  ┌─────────────────────────────────┐
  │  PLEOMORPHISM                   │
  │  (variable cell/nuclear size)   │
  │                                 │
  │   ■ Large hyperchromatic nucleus│
  │   ■ N:C ratio markedly increased│
  │   ■ Coarse, clumped chromatin   │
  │   ■ Prominent nucleoli          │
  │   ■ Abnormal mitotic figures    │
  │     (tripolar/quadripolar)      │
  │   ■ Giant cells (tumor giant    │
  │     cells) - mono/multinucleate │
  │   ■ Loss of polarity            │
  └─────────────────────────────────┘

Features in Detail:

Exam tip: The 3 most important features = Pleomorphism + Hyperchromatism + Abnormal mitoses

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PART 5: BENIGN vs MALIGNANT - DIFFERENCES (★★★★)

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PART 6: METASTASIS - Definition, Mechanism, Routes (★★★)

Definition

Metastasis = Spread of a malignant tumor to a site discontinuous from the primary tumor, via lymphatics, blood vessels, or body cavities. It is the most reliable indicator that a tumor is malignant.

The Metastatic Cascade (Steps of Metastasis)

METASTATIC CASCADE:

PRIMARY TUMOR
     ↓
1. DETACHMENT from primary mass
   (↓ E-cadherin expression; SNAIL/TWIST TF activation)
     ↓
2. INVASION of ECM (basement membrane)
   - Secretion of MMPs (matrix metalloproteinases)
   - Type IV collagenase digests BM
   - Cathepsin D, urokinase plasminogen activator
     ↓
3. INTRAVASATION
   (enter blood/lymph vessels)
     ↓
4. SURVIVAL IN CIRCULATION
   (evade immune surveillance, form tumor emboli)
     ↓
5. ARREST in distant organ capillaries
   (via integrins binding to endothelial laminin)
     ↓
6. EXTRAVASATION
   (exit vessels at distant site)
     ↓
7. PROLIFERATION at new site
   (seed + soil hypothesis - Paget, 1889)
   + Angiogenesis (VEGF)
     ↓
METASTATIC COLONY

Invasion of ECM - 3 Key Steps (Diagram from Robbins):

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PART 7: ROUTES / PATHWAYS OF SPREAD OF MALIGNANT NEOPLASMS (★★★)

1. Lymphatic Spread (most common in Carcinomas)

• Tumor cells enter lymphatics → regional lymph nodes → distant nodes → thoracic duct → bloodstream
• Sentinel lymph node = first draining lymph node from primary tumor (assessed by dye/radiolabeled tracers)
• Skip metastases: Cells bypass regional nodes and lodge in distant nodes
• Examples:
  • Breast carcinoma → Axillary lymph nodes (upper outer quadrant)
  • Lung carcinoma → Bronchial → Tracheobronchial → Hilar nodes
  • Gastric carcinoma → Left supraclavicular node (Virchow's node = Troisier's sign)
  • Testicular carcinoma → Para-aortic nodes

2. Hematogenous Spread (most common in Sarcomas)

• Tumor cells invade thin-walled veins (not arteries)
• Portal vein drainage → Liver (most common hematogenous metastasis site)
• Systemic veins → Lungs (second most common)
• Paravertebral plexus → Spine (prostate, thyroid)
• Organ tropism ("seed and soil"):
  • Breast carcinoma → Bone, liver, lungs, brain
  • Bronchogenic carcinoma → Adrenals, brain
  • Prostate carcinoma → Bone (osteoblastic)
  • Neuroblastoma → Liver, bone
  • Renal cell carcinoma → Grows as a "plug" in IVC up to heart

3. Transcoelomic / Peritoneal Spread

• Tumor implants on peritoneal, pleural, or pericardial surfaces without invading underlying tissue
• Classic example: Ovarian carcinoma → Peritoneal seeding
• Pseudomyxoma peritonei (mucinous implants in peritoneum)
• Mesothelioma of pleura

4. Spread Along Body Cavities / CSF

• CNS tumors (medulloblastoma, ependymoma) → Penetrate ventricles → carried by CSF → implant on meninges of brain/spinal cord

5. Spread Along Epithelial Surfaces (Direct / Contiguous)

• Tumor invades directly into adjacent structures
• Carcinoma rectum → bladder; Carcinoma cervix → urinary bladder/rectum

Gross Pathology - Liver with Metastasis:

Gross: Multiple pale creamy-white nodules scattered throughout liver parenchyma with umbilication (central depression due to necrosis) - "Cannon-ball deposits."

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PART 8: CHEMICAL CARCINOGENESIS (★★★)

Definition

Classification of Chemical Carcinogens

• Alkylating agents: Nitrogen mustard, cyclophosphamide, busulfan (iatrogenic cancers)
• Acylating agents: Dimethylcarbamyl chloride

• Polycyclic aromatic hydrocarbons (PAH): Benzo[a]pyrene (tobacco smoke) → lung cancer
• Aromatic amines / azo dyes: Beta-naphthylamine → bladder cancer; Dimethylaminoazobenzene (DAB, "butter yellow") → liver cancer
• Nitrosamines: N-nitrosodimethylamine → liver, esophagus
• Aflatoxin B1 (from Aspergillus flavus on peanuts/grains) → hepatocellular carcinoma; causes characteristic TP53 codon 249 mutation
• Vinyl chloride → Angiosarcoma of liver
• Benzene → Leukemia
• Asbestos → Mesothelioma + lung carcinoma
• Chromium, nickel, arsenic → Lung cancer

• Estrogen → Endometrial carcinoma, breast carcinoma

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Steps of Chemical Carcinogenesis (★★★)

STEP 1: INITIATION

• Exposure to carcinogen → metabolic activation → electrophilic intermediate forms
• Electrophile forms DNA adducts (covalent bond with DNA)
• If DNA repair fails → Permanent mutation in initiated cell
• Initiation is rapid, irreversible, permanent
• Single exposure sufficient
• Key mutations: RAS, TP53 oncogenes

STEP 2: PROMOTION

• Repeated/sustained exposure to promoters (not mutagenic themselves)
• Promoters cause clonal expansion of initiated cells
• Initiated cells accumulate more mutations → Preneoplastic clone
• Further proliferation + additional mutations → Malignant clone
• Promotion is reversible (if promoter is withdrawn before malignancy established)
• Examples of promoters: Phorbol esters (TPA), hormones, phenols

INITIATION → PROMOTION SEQUENCE:
(Carcinogen)   (Promoter - repeated)
    ↓                  ↓
DNA mutation → Clonal expansion → Additional mutations → CANCER
(irreversible)  (reversible if   (irreversible)
                 stopped early)

Key Mnemonics:

• INITIATION = Irreversible, Immediate
• PROMOTION = Prolonged, Partially reversible

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PART 9: ONCOGENIC VIRUSES (Viral Carcinogenesis)

DNA Viruses (most important)

RNA Viruses (Retroviruses)

Mechanisms:

• HPV: E6 protein degrades p53 (tumor suppressor); E7 binds and inactivates RB → uncontrolled cell cycle
• EBV: Latent membrane protein (LMP-1) acts as constitutively active receptor mimicking CD40 → activates NF-κB, Bcl-2 → immortalization
• HBV: Integration into host genome; HBx protein activates growth-promoting genes; chronic injury + inflammation → HCC
• HTLV-1: Tax protein activates cell cycle regulatory genes; suppresses TP53

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PART 10: PARANEOPLASTIC SYNDROMES (★★)

Definition

Symptoms and signs in cancer patients not explained by local tumor effects, metastasis, or therapy - caused by ectopic hormone secretion or immune/autoimmune reactions triggered by the tumor.

Common Paraneoplastic Syndromes:

Exam tip: Small cell lung carcinoma produces the most paraneoplastic syndromes (ACTH, ADH, Lambert-Eaton)

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PART 11: TUMOR MARKERS - Role in Diagnosis (★★)

Definition

Tumor markers = Biochemical substances (proteins, hormones, enzymes, antigens) produced by tumor cells or in response to tumor cells, detectable in blood, urine, or tissues.

Important Tumor Markers:

Role of Tumor Markers in Diagnosis:

1. Screening (limited use due to low sensitivity/specificity): PSA for prostate cancer
2. Diagnosis: AFP for hepatocellular carcinoma; β-hCG for choriocarcinoma
3. Staging: LDH in lymphoma; AFP + β-hCG in testicular germ cell tumors
4. Monitoring treatment response: CEA levels fall with successful surgery
5. Detecting recurrence: CEA / PSA reappearance after surgery = recurrence
6. Prognosis: High AFP = advanced HCC; high LDH = poor prognosis lymphoma

Limitations: No tumor marker is 100% specific or sensitive. False positives (e.g., PSA in BPH; CEA in smokers) and false negatives occur.

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PART 12: LABORATORY DIAGNOSIS OF CANCER (★★★)

A. HISTOPATHOLOGY (Gold Standard)

• Biopsy and H&E staining - most definitive method
• Types of biopsy:
  • Excision biopsy: Complete excision of small lesion with margins
  • Incision biopsy: Partial removal of large lesion
  • Core needle biopsy (Tru-cut): Cylinder of tissue
  • Fine Needle Aspiration Cytology (FNAC): Aspirate cells only; no tissue architecture
• Frozen section: Rapid intraoperative diagnosis (30 min) to assess margins during surgery

B. CYTOLOGY

• Exfoliative cytology: Cells shed naturally
  • Pap smear (cervical carcinoma) - gold standard screening test for cervical cancer
  • Sputum cytology (lung carcinoma)
  • Urine cytology (bladder carcinoma)
  • Pleural/peritoneal fluid analysis
• FNAC (Fine Needle Aspiration Cytology):
  • For thyroid, lymph node, breast, salivary gland masses
  • Minimally invasive; quick result
  • Limitation: No tissue architecture, so cannot distinguish invasion

C. IMMUNOHISTOCHEMISTRY (IHC)

• Uses antibodies tagged with color/fluorescent labels to detect specific antigens in tumor tissue
• Used to:
  • Identify tissue of origin of metastasis (e.g., PSA = prostate origin; TTF-1 = lung/thyroid)
  • Classify tumors: ER/PR/HER2 in breast cancer (determines therapy)
  • Identify lymphoma subtypes: CD20 (B-cell), CD3 (T-cell)
  • Prognostication: Ki-67 index (proliferation rate)

D. FLOW CYTOMETRY

• Used in leukemias and lymphomas to identify surface immunophenotype (CD markers)
• Determines cell lineage: B-cell vs T-cell vs myeloid
• Detects aneuploidy (abnormal DNA content)

E. MOLECULAR / GENETIC DIAGNOSIS

• PCR (Polymerase Chain Reaction):
  • Detect BCR-ABL transcripts in CML
  • Detect minimal residual disease after treatment
  • Detect gene rearrangements in lymphoid malignancies
• FISH (Fluorescence In Situ Hybridization):
  • Detect chromosomal translocations: t(9;22) in CML; t(8;14) in Burkitt lymphoma
  • HER2 amplification in breast cancer
  • ALK gene rearrangement in lung cancer
• Next-generation sequencing / Gene panels:
  • Comprehensive mutation profiling (EGFR, KRAS, BRAF, etc.)
  • Guides targeted therapy decisions
• Liquid biopsy:
  • Detection of circulating tumor DNA (ctDNA) in blood
  • Detects recurrence early; non-invasive

F. TUMOR MARKERS (BIOCHEMICAL)

G. IMAGING

• CT scan, MRI, PET-CT scan, Ultrasound
• PET-CT: Uses 18F-FDG (glucose analogue) - cancer cells show high uptake (Warburg effect)

Summary Table - Lab Diagnosis:

CANCER - LAB DIAGNOSIS:

  A. HISTOPATHOLOGY - Biopsy (H&E) - GOLD STANDARD
  B. CYTOLOGY - Pap smear, FNAC, sputum cytology
  C. IHC - Tissue typing, receptor status (ER, PR, HER2)
  D. FLOW CYTOMETRY - Leukemia/lymphoma immunophenotyping
  E. MOLECULAR - PCR, FISH, NGS, Liquid biopsy
  F. TUMOR MARKERS - AFP, CEA, PSA, CA-125, β-hCG
  G. IMAGING - CT, MRI, PET-CT

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PART 13: EASY-TO-DRAW DIAGRAMS FOR EXAM

Diagram 1: Benign vs Malignant Tumor (H&E appearance)

BENIGN TUMOR               MALIGNANT TUMOR
(e.g. Adenoma)             (e.g. Adenocarcinoma)

○ ○ ○ ○ ○               ⊕ ◉ ◎ ○ ⊕
○ ○ ○ ○ ○               ◉ ◉ ⊕ ◎ ○
○ ○ ○ ○ ○               ⊕ ○ ◉ ⊕ ◉
─────────────               ─ ─ ─ ─ ─ ─ (broken BM)
INTACT BM                   INVADED STROMA
[uniform cells]             [pleomorphic, hyperchromatic
 gland formation]            nuclei, abnormal mitoses,
                             invasion of BM]

Diagram 2: Metastatic Cascade (Draw as flow chart)

PRIMARY TUMOR
    ↓ (↓E-cadherin)
DETACHMENT
    ↓ (MMPs digest BM)
ECM INVASION
    ↓
INTRAVASATION → Blood/Lymph
    ↓ (tumor emboli)
CIRCULATION
    ↓ (integrins)
ARREST in capillaries
    ↓
EXTRAVASATION
    ↓ (VEGF, angiogenesis)
SECONDARY TUMOR

Diagram 3: Chemical Carcinogenesis (2-Step)

CHEMICAL CARCINOGEN (e.g. Benzo[a]pyrene)
    ↓ Liver CYP450 enzymes (Metabolic activation)
ULTIMATE CARCINOGEN (electrophile)
    ↓
DNA ADDUCTS
    ↓ (failed repair)
MUTATION in RAS / TP53
    ↓ = INITIATION (permanent, irreversible)

PROMOTER (e.g. phorbol ester) - repeated exposure
    ↓
CLONAL EXPANSION of initiated cells
    ↓
ADDITIONAL MUTATIONS
    ↓
MALIGNANT NEOPLASM

Diagram 4: Routes of Metastasis

PRIMARY TUMOR
    ├─── 1. LYMPHATIC → Lymph nodes → Thoracic duct → Blood
    ├─── 2. HEMATOGENOUS → Vein → Liver / Lung / Bone
    ├─── 3. TRANSCOELOMIC → Peritoneum / Pleura / Pericardium
    └─── 4. CSF SPREAD → Meninges

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QUICK REVISION BOX: HIGH-YIELD ASSOCIATIONS

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Source: Robbins & Kumar Basic Pathology (10th Edition), Chapter 6 - Neoplasia, pp. 214-278. All diagrams and gross images from Robbins Pathology textbook.

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• For 5-mark questions: Definition + Classification table + 3-4 key features
• For 10-mark questions: Full notes above with diagrams
• Always draw: Metastatic cascade flowchart, Initiation-Promotion diagram, Benign vs Malignant comparison table
• Frequently asked in MUHS: Metastasis routes, Chemical carcinogenesis steps, Benign vs Malignant differences, Tumor markers table, Paraneoplastic syndromes table