Unusual Endocervical Adenocarcinomas

Abstract

Endocervical adenocarcinomas of the usual type are etiologically related to infection with oncogenic human papillomaviruses (HPVs). These tumors are typically diffusely positive for p16 and carcinoembryonic antigen (CEA) immunostains. The goal of our study was to determine the HPV status and immunohistochemical profiles of unusual histologic subtypes of endocervical adenocarcinoma. The study consisted of a total of 26 cases of unusual subtypes including clear cell carcinoma (CCC, n=9), gastric-type adenocarcinoma (GAS, n=11), minimal deviation adenocarcinoma (MDA, n=3), mesonephric adenocarcinoma (MSN, n=1), serous adenocarcinoma (SER, n=1), and malignant mixed Müllerian tumor (n=1). In addition, 5 cases of usual-type endocervical adenocarcinoma (UEA) were included in the study as a control group. The cases were tested for HPV using SPF-10 PCR and LiPA assays, and immunostained for p16, HIK1083, hepatocyte nuclear factor 1-β, p53, CEA, estrogen receptor (ER), and progesterone receptor (PR). HPV DNA was not detected in any of the unusual adenocarcinoma subtypes, with the exception of a single case of SER in which HPV16 was detected. p16 positivity did not correlate with HPV status, as 42% of HPV-negative tumors showed patchy/diffuse p16 overexpression; however, p16 positivity was uncommon in GAS/MDA. HIK1083 positivity was limited to GAS and MDA, indicating relative specificity for tumors with gastric mucin expression. Hepatocyte nuclear factor 1-β was positive in the majority of CCCs and also in other tumor variants and in some UEA as well, indicating a lack of specificity for clear cell differentiation. CEA was consistently negative in CCCs and in a single MSN, but positive in GAS, MDA, SER, and UEA, suggesting that it may serve as a negative marker of clear cell differentiation. p53 was diffusely positive in almost half of the GAS cases, whereas UEA showed mostly negative staining and other variants showed focal staining. PR was negative in all variant cases and in all UEA. ER expression, although mostly negative, showed focal staining in a few variant cases and UEA. Unusual variants of endocervical adenocarcinoma are not related to HPV infection, with only rare exceptions, and p16 overexpression in non-UEA does not correlate with HPV status. Negative staining for PR and ER may serve as a general marker of endocervical neoplasia. GAS/MDA may be differentiated from all other adenocarcinomas with either positive HIK1083 stain or negative/focal p16 stain. Positive CEA stain differentiates GAS/MDA from CCC and negative PR and ER stains differentiate GAS/MDA from benign endocervical glands. CCC may be distinguished from all other adenocarcinomas, except MSN, with a negative CEA stain. Strong and diffuse p53 positivity in SER may be useful in differentiation from UEA. MSN may be identified with negative CEA, ER, and PR stains.