Human papillomavirus (HPV)

The Pathology Dictionary Team
April 13, 2023

What is human papillomavirus?

Human papillomavirus (HPV) is a very common sexually transmitted virus. There are more than 100 types of HPV and some types are more likely than others to cause cancer. The virus infects squamous cells which are normally found in the skin, mouth and throat, cervix, penis, and anal canal.

How is human papillomavirus spread?

HPV is typically transmitted through vaginal, anal, or oral sex, and can also be spread through skin-to-skin contact during sexual activity.

What are the symptoms of human papillomavirus infection?

Most people who become infected with HPV do not develop any symptoms and the virus goes away on its own. However, in some cases, HPV can cause genital warts or lead to more serious health problems, such as cervical, anal, or throat cancer.

What is high-risk human papillomavirus?

High-risk HPV refers to certain types of human papillomavirus that are more likely to cause cancer. While most HPV infections do not cause any symptoms and go away on their own, high-risk types of HPV tend to stay inside cells longer which can cause the cells to become cancer over time.

The types of cancer most commonly associated with high-risk HPV include cervical cancer, throat cancer, penile cancer, and anal cancer. In addition, high-risk HPV can also cause genital warts, but this is less common. It’s important to note that having a high-risk HPV infection does not necessarily mean that you will develop cancer, but it does increase your risk.

High-risk types of HPV include:
  • HPV 16
  • HPV 18
  • HPV 31
  • HPV 33
  • HPV 35
  • HPV 39
  • HPV 45
  • HPV 51
  • HPV 52
  • HPV 56
  • HPV 58
  • HPV 59
  • HPV 66
  • HPV 68

What are the most common high-risk types of human papillomavirus?

HPV 16 and 18 are the two most common high-risk types of HPV and are responsible for causing the majority of HPV-related cancers, including cervical, anal, and some types of throat cancer.

What types of cancer are caused by human papillomavirus?

HPV is responsible for the majority of cervical, penile, anal, and throat cancers in adults. In these locations, HPV causes a type of cancer called squamous cell carcinoma (SCC) because the tumour is made up of abnormal squamous cells. In some parts of the body, such as the throat, the cancer is described as non-keratinizing squamous cell carcinoma because the tumour cells do not undergo a process called keratinization which makes them look less pink and more blue under the microscope.

human papillomavirus non-keratinizing squamous cell carcinoma
Human papillomavirus associated non-keratinizing squamous cell carcinoma involving the tonsil.

What precancerous conditions are caused by human papillomavirus?

Precancerous conditions caused by HPV are usually divided into two groups: low grade squamous intraepithelial lesion (LSIL) and high grade squamous intraepithelial lesion (HSIL) and the risk associated with developing cancer is higher with HSIL.

How do doctors test for human papillomavirus?

There are several different ways to test for HPV. Most doctors will start off by examining the area to look for signs of HPV infection. If the area appears abnormal, some cells may be removed in a procedure called a Pap smear or a biopsy. Cells infected with a high-risk type of HPV will often produce large amounts of a protein called p16. For this reason, p16 is considered a ‘surrogate marker’ for HPV because cells that are p16-positive are likely to be infected by HPV. Other tests used to look for HPV include polymerase chain reaction (PCR) and in situ hybridization (ISH). Both of these tests look for genetic material produced by HPV inside infected cells.

human papillomavirus p16 positive
This picture shows human papillomavirus-infected and p16-positive cells in the anal canal. The infected cells in this picture are brown while the non-infected cells are blue.
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