HPV stands for human papillomavirus. HPV is a sexually transmitted virus. It is very common and most sexually active adults will be exposed to the 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.
Pathologists perform a test called immunohistochemistry to see if a tumour is caused by HPV. 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.