Mesonephric adenocarcinomas of the uterine cervix and corpus: HPV-negative neoplasms that are commonly PAX8, CA125, and HMGA2 positive and that may be immunoreactive with TTF1 and hepatocyte nuclear factor 1-β.

Mesonephric adenocarcinomas are rare neoplasms that most commonly arise in the uterine cervix and exceptionally rarely in the uterine corpus. Although the morphologic features of these neoplasms are well described, there has been relatively limited investigation of the immunoprofile. We report a series of 8 mesonephric adenocarcinomas arising in the uterine cervix (7 cases) and corpus (1 case) and undertake a comprehensive immunohistochemical analysis. This includes markers that have not been investigated previously in mesonephric adenocarcinomas but that are commonly used in gynecologic pathology and may be undertaken when other, mainly Mullerian, adenocarcinomas are considered in the differential diagnosis. Linear array human papillomavirus (HPV) genotyping was also performed. Our results broadly confirm the immunohistochemical profile demonstrated in previous studies with the majority of mesonephric adenocarcinomas staining positively with CD10 (6 of 8), epithelial membrane antigen (8 of 8), vimentin (8 of 8), and calretinin (7 of 8). Estrogen receptor was positive in 2, carcinoembryonic antigen in 3, and inhibin in 4 cases. p16 was positive in 5 cases (1 diffuse and strong), despite all being HPV negative (in 1 case, there was insufficient DNA for HPV analysis). Novel findings in our study were the demonstration of nuclear positivity with PAX8 and HMGA2 in 7 cases, CA125 immunoreactivity in all 8 cases, and TTF1 and hepatocyte nuclear factor 1-β staining in 3 cases. As PAX8, CA125, HMGA2, and hepatocyte nuclear factor 1-β are commonly positive in a variety of Mullerian adenocarcinomas arising in the female genital tract, this may result in diagnostic confusion. All cases were WT1 negative.