Learning Objectives
Master the Tumor Nomenclature rules to distinguish between benign and malignant growths. Differentiate between Carcinoma and Sarcoma based on their tissue of origin, and understand the unique definitions of Hamartoma and Choristoma.
1. Benign vs. Malignant Characteristics
Tumors are classified based on their biological behavior, degree of differentiation, and ability to spread.
| Feature | Benign | Malignant (Cancer) |
|---|---|---|
| Differentiation | Well-differentiated (resembles parent tissue). | Poorly differentiated (anaplasia). |
| Growth & Invasion | Slow growth; well-demarcated; no invasion. | Erratic growth; local invasion. |
| Metastasis | Absent. | Frequently present. |
| Other Features | Low mitotic activity; no necrosis. | Necrosis is common; ↓ apoptosis. |
Activity:
2. Nomenclature by Tissue Origin
The suffix used in a tumor’s name reveals its origin and malignancy status. Generally, “-oma” denotes benign, while “-sarcoma” or “-carcinoma” denotes malignancy.
| Cell / Tissue Type | Benign Name | Malignant Name |
|---|---|---|
| Epithelium | Adenoma, Papilloma | Adenocarcinoma, Papillary carcinoma |
| Mesenchyme (Connective) | Fibroma, Lipoma | Fibrosarcoma, Liposarcoma |
| Blood Vessels | Hemangioma | Angiosarcoma |
| Muscle | Leiomyoma (Smooth), Rhabdomyoma (Striated) | Leiomyosarcoma, Rhabdomyosarcoma |
| Blood Cells | (None – typically malignant) | Leukemia, Lymphoma |
Activity:
3. Non-Neoplastic Malformations
These are developmental anomalies that may look like tumors but are not true neoplasms.
| Term | Definition | Example |
|---|---|---|
| Hamartoma | Disorganized growth in the native location. | Peutz-Jeghers polyps in the colon. |
| Choristoma | Normal tissue in a foreign (ectopic) location. | Gastric tissue in Meckel diverticulum. |
Activity
High-Yield Mnemonics & Tips:
- Carcinoma vs. Sarcoma: Carcinoma is for Coatings (epithelial). Sarcoma is for Supporting tissues (connective).
- Malignant “-omas”: Remember Melanoma, Lymphoma, and Seminoma are always malignant despite the suffix.
- Choristoma: A “chorist” is a singer away from their home choir—it is normal tissue in the wrong place.