Define neoplasm.
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Here is a comprehensive definition drawn directly from authoritative textbooks:
Neoplasm
Neoplasm (from Greek neos = new, plasma = formation) literally means "new growth." It refers to an abnormal mass of tissue whose growth is uncoordinated, exceeds that of normal tissues, persists after the initiating stimulus ceases, and serves no useful physiologic purpose.
Neoplastic cells are said to be transformed — they replicate incessantly because they have acquired resistance to the regulatory signals that normally control cell proliferation. While neoplasms enjoy a degree of autonomy, they remain dependent on the host for nutrition and blood supply, and hormonally responsive neoplasms may require endocrine support.
The term tumor is used interchangeably with neoplasm in modern usage (historically, "tumor" simply meant swelling from any cause, including inflammation). The study of tumors is oncology (Greek oncos = tumor).
Classification: Benign vs. Malignant
All neoplasms are broadly categorized as either benign or malignant:
| Feature | Benign | Malignant |
|---|---|---|
| Local invasion | No | Yes |
| Metastasis | No | Yes |
| Behavior | Localized, surgically curable | Locally invasive, can spread distantly |
| Collective term | — | Cancer |
- Benign tumors remain localized and can generally be cured by local surgical removal, though they may still cause significant morbidity if near vital structures.
- Malignant tumors (cancers) may invade locally and metastasize to distant sites. The word cancer derives from the Latin for "crab," reflecting the way malignant tumors infiltrate surrounding tissues.
Structure of All Neoplasms
Every neoplasm — benign or malignant — has two fundamental components:
- Parenchyma — the transformed, neoplastic cells themselves; determines biologic behavior and gives the tumor its name.
- Stroma — host-derived supporting tissue including connective tissue, blood vessels, and inflammatory cells; essential for tumor growth and involves bidirectional signaling with tumor cells.
Nomenclature Highlights
- Benign tumors: suffix -oma added to cell of origin (e.g., fibroma, chondroma, adenoma).
- Malignant tumors of epithelial origin: carcinoma (e.g., adenocarcinoma).
- Malignant tumors of mesenchymal origin: sarcoma (e.g., fibrosarcoma, leiomyosarcoma).
Sources: Robbins & Kumar Basic Pathology; Sabiston Textbook of Surgery; Harper's Illustrated Biochemistry
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