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| __NOTOC__
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| {{Kaposi's sarcoma}}
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| {{CMG}}
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| ==Pathophysiology==
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| Kaposi's sarcoma (KS) is a tumor caused by [[Kaposi's sarcoma-associated herpesvirus|Human herpesvirus 8]] (HHV8), also known as [[Kaposi's sarcoma-associated herpesvirus]] (KSHV). Despite its name, it is generally not considered a true [[sarcoma]], which is a tumor arising from [[mesenchyme|mesenchymal tissue]]. KS actually arises as a cancer of [[lymphatic]] [[endothelium]] and forms vascular channels that fill with blood cells, giving the tumor its characteristic bruise-like appearance. [[Image:Kaposi's sarcoma patho.jpg|thumb|200px|left|[[Micrograph]] of a Kaposi's sarcoma showing the characteristic spindle cells, high [[vascular]]ity and [[intracellular]] [[hyaline]] globs. [[H&E stain]].]]
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| KS lesions contain tumor [[cell (biology)|cells]] with a characteristic abnormal elongated shape, called ''spindle cells''. The tumor is highly [[Blood vessel|vascular]], containing abnormally dense and irregular blood vessels, which leak red blood cells into the surrounding tissue and give the tumor its dark color. [[Inflammation]] around the tumor may produce swelling and pain.
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| Although KS may be suspected from the appearance of lesions and the patient's risk factors, definite diagnosis can be made only by [[biopsy]] and microscopic examination, which will show the presence of spindle cells. Detection of the KSHV protein [[LANA]] in tumor cells confirms the diagnosis.
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| ===Transmission===
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| In Europe and North America, KSHV is transmitted through saliva. Thus, kissing is a theoretical risk factor for transmission. Higher rates of transmission among gay and bisexual men have been attributed to "deep kissing" sexual partners with KSHV.<ref>http://content.nejm.org/cgi/content/abstract/343/19/1369</ref> Another alternative theory suggests that use of saliva as a sexual lubricant might be a major mode for transmission. Prudent advice is to use commercial lubricants when needed and avoid deep kissing with partners with KSHV infection or whose status is unknown.
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| KSHV is transmissible during organ transplantation
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| <ref name="bloodjournal.hematologylibrary.org">http://bloodjournal.hematologylibrary.org/cgi/content/full/90/7/2826</ref> and to a lesser extent through blood transfusion.<ref>http://content.nejm.org/cgi/content/abstract/355/13/1331</ref> Testing for the virus before these procedures is likely to effectively limit [[iatrogenic]] transmission.
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| They used [[representational difference analysis]] (a method to subtract out all of the human DNA from a sample) to isolate the viral genes.
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| They then used these small DNA fragments as starting points to sequence the rest of the viral genome in 1996.
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| This, the eighth human herpes virus (HHV-8)—now known as Kaposi's sarcoma-associated herpesvirus (KSHV)—has since been found in all KS lesions tested, and is considered the cause of the disease.
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| KSHV is a unique human tumor virus that has incorporated cellular genes that cause tumors into its genome ("molecular piracy");
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| the stolen cellular genes may help the virus escape from the immune system, but in doing so it also causes cells to proliferate.
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| It is related to [[Epstein-Barr virus]], a very common herpes virus that can also cause human cancers.
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| ==References== | | ==References== |