Neoplasia: Classification and Nomenclature covers neoplasia classification and nomenclature for INI CET (AIIMS PG).
Neoplasia: New, autonomous, excessive growth of cells that persists after the initiating stimulus is removed.
Key Distinction:
- Hyperplasia: Increased cell number — stimulus-dependent (reversible)
- Neoplasia: Increased cell number — autonomous growth (independent of stimulus, irreversible)
Tumor Nomenclature:
| Type | Description | Example |
|---|---|---|
| Benign | Confined, encapsulated, no metastasis | Lipoma, chondroma |
| Malignant | Invasive, can metastasize | Carcinoma, sarcoma |
Specific Nomenclature:
- Adenoma: Benign glandular tumor (e.g., thyroid adenoma)
- Papilloma: Benign乳头状 growth (e.g., skin warts)
- Cystadenoma: Benign cystic glandular tumor (e.g., ovarian cystadenoma)
- Carcinoma: Malignant tumor of epithelial origin (most common — ~80% of cancers)
- Adenocarcinoma: Carcinoma with glandular differentiation
- Squamous cell carcinoma: Carcinoma with squamous differentiation
- Sarcoma: Malignant tumor of mesenchymal origin (e.g., osteosarcoma, leiomyosarcoma)
- Leukemia: Hematopoietic malignancy without a solid tumor
- Lymphoma: Hematopoietic malignancy of lymphoid tissue
Grading: Degree of differentiation (microscopic)
- GX: Cannot be assessed
- G1: Well differentiated (low grade)
- G2: Moderately differentiated (intermediate grade)
- G3: Poorly differentiated
- G4: Undifferentiated (high grade)
Staging: Extent of spread (clinical/radiological — TNM system)
- T: Size and local extent of primary tumor
- N: Regional lymph node involvement
- M: Distant metastasis
⚡ Exam Tip for INI CET (AIIMS PG): Grading = microscopic (how abnormal cells look). Staging = spread (clinical/radiological). Both determine prognosis and treatment.
Benign vs Malignant Characteristics:
| Feature | Benign | Malignant |
|---|---|---|
| Differentiation | Well differentiated | Poorly/undifferentiated |
| Rate of growth | Slow, expansile | Rapid, infiltrative |
| Capsulation | Often encapsulated | Not encapsulated |
| Nuclear features | Uniform, few mitoses | Pleomorphic, hyperchromatic, many mitoses |
| Necrosis | Usually absent | Often present |
| Metastasis | Absent | Present |
| Recurrence | Rare | Common |
Carcinoma In Situ (CIS): Pre-invasive carcinoma — cells are malignant but basement membrane is intact (no invasion). Example: Cervical intraepithelial neoplasia (CIN III), DCIS (breast).