We investigated 148 adenocarcinoma cases, including 21 cases of adenocarcinoma in situ (AIS) and 127 cases of invasive adenocarcinoma, using immunohistochemistry to detect tumor-infiltrating immune cells and the expression of programmed cell death 1 ligand-1 (PD-L1) and p16 on tumor cells.
Nevertheless, any positive p16 expression was sensitive, ranging from 0.94 to 0.98 with narrow confidence intervals (CIs), for adenocarcinoma in situ (AIS) and mucinous adenocarcinomas in comparison with normal/benign endocervix and benign endocervical and endometrioid lesions.
In cervical glandular lesions, p16 is useful, as part of a panel, in the distinction between adenocarcinoma in situ (diffusely positive) and benign mimics, including tuboendometrial metaplasia and endometriosis, which are usually p16-negative or focally positive. p16 may be used, in combination with other markers, to distinguish between a cervical adenocarcinoma (diffuse positivity) and an endometrioid-type endometrial adenocarcinoma (negative or focally positive).
Further immunostaining for p16INK4A and p53 was performed to assess alternative pathways of carcinogenesis potentially unrelated to HPV. hrHPV DNA was found in all (100%) ACISs and 72 (94%) cervical AdCAs, whereas none of 20 endometrial AdCAs scored hrHPV-positive.
The diffuse distribution of p16 immunostaining in HPV16/18-positive glandular neoplasms supports a strong association with HPV infection and indicates that this biomarker may discriminate ACIS from its benign mimics.