What does p16 stain for?

P16INK4a immunohistochemistry (IHC) is widely used to facilitate the diagnosis of human papillomavirus (HPV)-associated cervical precancerous lesions. While most p16 results are distinctly positive or negative, certain ones are ambiguous: they meet some but not all requirements for the “block-positive” pattern.

What does p16 positivity mean?

In the vulva, p16 is positive in HPV-associated vulval intraepithelial neoplasia (VIN) but negative in VIN not associated with HPV. Similarly, HPV-associated invasive squamous carcinomas are p16-positive, whereas the more common non-HPV-associated neoplasms are largely negative or focally positive.

What does p16 patchy positive mean?

Immunohistochemistry A variable, patchy positive pattern of staining was interpreted as the wild-type pattern (“negative”). For p16, a positive pattern was block-like positive nuclear, ± cytoplasmic staining in virtually all tumor cells. Variable and/or patchy positive staining was interpreted as negative.

What does p16 equivocal mean?

Discussion. Our results suggest that the pattern of p16 immunohistochemical staining in HNSCC can reliably predict HPV status in cases deemed as “equivocal” because they do not fall into the positive/negative dichotomy according to a numerical percentage cutoff used in many studies [17–22].

Is p16 a marker for HPV?

p16, a cell cycle inhibitor, has been postulated as a surrogate marker for HR-HPV, since p16 is aberrantly overexpressed in such lesions, especially in HR-HPV-positive OPSCC. However, p16 as a surrogate marker for HR-HPV infection in cancers of the oral cavity remains controversial.

Is p16 a nuclear or cytoplasmic stain?

p16 overexpression is strictly defined as continuous, strong, cytoplasmic and nuclear staining in the abnormal cells, which results in a “block” pattern of positivity.

Is p16 same as HPV?

Expression of p16INK4A (p16 positive) is highly correlated with human papilloma virus (HPV) infection in head and neck squamous cell carcinoma (HNSCC), however, p16-positivity is not limited to HPV positive tumors and therefore, not a perfect surrogate for HPV.

Is p16 the same as hpv16?

On the other hand, p16 protein overexpression is caused by viral E7 protein (11). Consequently, p16 is assumed to be an indirect marker of HPV-induced SCCHN. Several studies describe p16 protein detection as a useful marker of HPV (especially HPV-16) activity (12-15).

What is p16 testing?

p16 (INK4a/CDKN2A) is a cell cycle regulatory protein that is overexpressed in cervical dysplasia related to human papilloma virus (HPV) infection. Nuclear and cytoplasmic staining is seen in dysplastic squamous cervical epithelial cells infected with HPV, but not in normal cells.

What is p16 negative?

Oropharyngeal (p16-) cancer staging refers to TNM staging of carcinomas originating in the oropharynx that are not human papillomavirus (HPV)-associated. This system most commonly pertains to squamous cell carcinomas that tested negative for p16, an immunohistochemical proxy for HPV infection, or were not tested.

Why is p16 overexpressed in HPV?

p16 inactivates cyclin-dependent kinases that phosphorylate Rb; therefore p16 can decelerate the cell cycle. Rb phosphorylation status in turn influences expression of p16. In human papilloma virus (HPV) infection, the HPV oncogenes E6 and E7 can inactivate pRB and thus lead to p16 overexpression.