Utility of HoxB13 in differential diagnosis of female genital tract lesions with putative prostatic differentiation

Female genital tract lesions with putative prostatic differentiation include vaginal tubulosquamous polyp (TSP), cervical ectopic prostatic tissue (EPT), and adenoid basal carcinoma (ABC). HoxB13 is a transcription factor specific for the prostate, not previously assessed in these lesions. A cohort of 13 TSPs, 6 EPTs, 17 ABCs, and 8 adenoid basal hyperplasia (ABH) was analyzed for expression of prostatic markers HoxB13, NKX3.1, p16, and androgen receptor (AR). Additional 28 cervical high-grade squamous intraepithelial lesions (HSILs), 21 cervical squamous cell carcinomas (SCCs), 19 endocervical adenocarcinomas (EACs), and 10 endometrial endometrioid adenocarcinomas (ECs) were included. The results were recorded as immunoreactive score (IRS). In TSPs and EPTs, HoxB13 and NKX3.1 were positive in 100% and 89.5% of cases, respectively. No HoxB13, NKX3.1, and p16 was observed in ABHs. In contrast, all ABCs showed diffuse p16 positivity. NKX3.1 was positive in 82.6% of ABCs (median IRS = 2), HoxB13 was positive in 100% of ABCs (median IRS = 8), and the difference was statistically significant (p < 0.001). Both HoxB13 and NKX3.1 were positive in 9.5% (2/21) SCCs and 21.1% (4/19) EACs. Additionally, 40% (4/10) ECs were HoxB13-positive (IRS = 1-2). Any positivity of HoxB13 was 80% specific and 100% sensitive for the ABC. NKX3.1 was only 82.4% sensitive, but 88% specific for the diagnosis of ABC. Additionally, HoxB13 was also seen in 29.8% HSILs. No ABC showed AR positivity, while this was observed in rare cells (IRS 1-2) in 30.8%, 16.6%, and 37.5% of TSCs, EPTs, and ABHs, respectively. HoxB13 can be a useful and reliable marker for identification of TSPs, EPTs and ABCs.