Human papillomavirus (HPV) is a sexually transmitted virus. It is very common and most sexually active adults will be exposed to this virus at some point in their lives. The virus is spread by direct contact. The virus infects squamous cells which are normally found in the skin, mouth and throat, anal canal, and cervix.
Diseases caused by HPV include condyloma accuminatum, low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL), and squamous cell carcinoma. Areas of the body affected include the skin, throat, cervix, vulva, and anal canal.
Pathologists commonly perform a test called immunohistochemistry to see if a tumour is caused by human papillomavirus. The test looks for a protein called p16 and cells that have been infected by the virus produce more p16 than normal cells. Pathologists call p16 a surrogate marker because it is used to prove the virus is inside a cell without looking for the virus directly. Other tests including polymerase chain reaction (PCR) and in situ hybridization (ISH) directly test for HPV by looking for genetic material from the virus inside cells.