Tumor
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225936232
2008-07-16T02:38:47Z
Una Smith
3349439
wiktionary
[[Image:Swollen ankle.jpg|thumb|200px|right|[[Swelling (medical)|Swollen]] left ankle following a [[Sprained ankle|sprain]] Here, the '''tumor''' is the result of [[edema]] caused by [[inflammation]].]]
[[Image:Hidradenoma.jpg|thumb|200px|right|[[Neoplasm|Neoplastic]] tumor of the cheek skin, here a [[benign neoplasm]] of the [[sweat glands]] called [[Hidradenoma]].]]
{{wiktionarypar|tumor}}
A '''tumor''' or '''tumour''' is the name for a swelling or lesion formed by an abnormal growth of cells (termed ''[[Neoplasm|neoplastic]]'') which may be benign or malignant.
==Etymology==
The term is derived, via the [[Old French]] ''tumour'', from the [[Latin]] ''tumor'' "swelling".<ref>{{Dorlands|t_22|12830354}}</ref> originally meant an abnormal swelling of the flesh. In contemporary English, tumor has evolved to become synonymous with '''solid [[neoplasia|neoplasm]]'''<ref>''Tumor'' in [http://www.nlm.nih.gov/medlineplus/ency/article/001310.htm MedlinePlus Medical Encyclopedia]]</ref>, all other forms of swelling being called '''[[Swelling (medical)|swelling]]'''<ref>''swelling'', in [http://www.nlm.nih.gov/medlineplus/ency/article/003103.htm MedlinePlus Medical Encyclopedia]</ref>. This tendency has also become common in medical literature. The noun '''tumefaction''', derived from the adjective '''tumefied''', is the current medical term for non-neoplastic tumors <ref>{{Dorlands|t_22|12830299}}</ref>. See also [[tumescence]]. ''Tumor'' is not precisely synonymous with [[cancer]]. A ''tumor'' can be benign (pre-malignant) or malignant, whereas ''cancer'' is by definition malignant.
==Cause==
A [[neoplasm]] is an abnormal proliferation of tissues. Where the cause is known, more often than not, a somatic mutation is involved.
Most but not all neoplasms cause a tumor; those that do not cause tumors cause [[leukemia]]s. Solid neoplasms (or tumors) may be [[benign tumor|benign]] or [[cancer|malignant (cancer)]]. For some tumors, such as [[teratoma]]s, the cancer status is ambiguous; benign or malignant is properly determined retrospectively, after some years of surveillance.
===Differential diagnoses of swellings===
Swellings may have many causes other than what we now call tumors such as:
* [[Inflammation]], by far the most common cause; tumor is one of the classic signs of inflammation.<ref name="Medical Dictionary Lookup!">{{cite web |url=http://www.emedicine.com/asp/dictionary.asp?keyword=tumor |title=eMedicine/Stedman Medical Dictionary Lookup! |accessdate=2008-01-08 |format= |work=}}</ref> The lump following a blow on the head is a typical example. [[Infection]] is another common cause of inflammation.
* [[Edema]], the accumulation of an excessive amount of fluid in the tissues, either with or without inflammation.
* [[Malformation]], a [[congenital]] anomaly in the architecture of a tissue. A typical example is an epidermal [[nevus]].
* [[Cyst]], the accumulation of fluid in a closed structure. [[Breast cyst|Breast cysts]] are a typical example.
* [[Hemorrhage]] in a closed structure.
Other forms of swelling are part of the normal functions of the body and may or may not be included as causes of tumor. Examples include enlargement of the [[uterus]] in [[pregnancy]] and [[erection]] of the [[penis]].
==References==
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{{Tumors}}
[[Category:Anatomical pathology]]
[[Category:Oncology]]
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