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| Neoplasm Classification and external resources |
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| ICD-10 | C00.-D48. |
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| ICD-9 | 140-239.99 |
| DiseasesDB | 28841 |
| MedlinePlus | 001310. |
| MeSH | D009369 |
Neoplasia (new growth in Greek) is the abnormal proliferation of cells, resulting in a structure known as a neoplasm. [1] [2] Because neoplasia includes very different diseases, it is difficult to find a definition that describe them all. The definition of the British oncologist R.A. Willis is widely cited: "A neoplasm is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues, and persists in the same excessive manner after cessation of the stimulus which evoked the change." [3]
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Types
A neoplasm can be benign, potentially malignant (pre-cancer) or malignant (cancer). [4]
- Benign neoplasms include uterine fibroids and melanocytic nevi (skin moles). They do not transform into cancer.
- Potentially malignant neoplasms include carcinoma in situ. They do not invade and destroy but, given enough time, will transform into a cancer.
- Malignant neoplasms are commonly called cancer. They invade and destroy the surrounding tissue, may form metastases and eventually kill the host.
Difficulty of definition
A precise and all-encompassing definition of neoplasm has proven elusive. A neoplasm has been defined as an uncontrolled and progressive growth, although this definition is criticized because some neoplasms, such as nevi, are not progressive.[5]
Some sources consider a neoplasm to be synonymous with a tumor or unusual mass of tissue.[6] This is criticized because many neoplasms form no mass, including cervical intraepithelial neoplasia, anal intraepithelial neoplasia, and leukemia.
Clonality
Neoplastic tumors often contain more than one type of cell, but their initiation and continued growth is usually dependent on a single population of neoplastic cells. These cells are presumed to be clonal - that is, they are descended from a single progenitor cell.
Sometimes, the neoplastic cells all carry the same genetic or epigenetic anomaly which becomes evidence for clonality. For lymphoid neoplasms, e.g. lymphoma and leukemia, clonality is proven by the amplification of a single rearrangement of their immunoglobulin gene (for B cell lesions) or T-cell receptor gene (for T cell lesions). The demonstration of clonality is now considered to be necessary to identify a lymphoid cell proliferation as neoplastic.[7]
It is tempting to define neoplasms as clonal cellular proliferations but the demonstration of clonality is not always possible. Therefore, clonality is not required in the definition of neoplasia.
See also
External links
References
- ^ "What is neoplasm? Find the definition for neoplasm at WebMD". Retrieved on 2008-01-08.
- ^ n_03/12561445 at Dorland's Medical Dictionary
- ^ Willis RA: The Spread of Tumors in the Human Body. London, Butterworth & Co, 1952
- ^ "Cancer - Activity 1 - Glossary, page 4 of 5". Retrieved on 2008-01-08.
- ^ n_03/12561445 at Dorland's Medical Dictionary
- ^ "Pancreas Cancer: Glossary of Terms". Retrieved on 2008-01-08.
- ^ Lee ES, Locker J, Nalesnik M, et al (1995). "The association of Epstein-Barr virus with smooth-muscle tumors occurring after organ transplantation". N. Engl. J. Med. 332 (1): 19–25. doi:. PMID 7990861.
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