NKX3.1 expression in cervical 'adenoid basal cell carcinoma': another gynaecological lesion with prostatic differentiation?

Adenoid basal cell carcinoma (ABC) is considered a rare cervical neoplasm which when present in 'pure' form, uniquely amongst apparently malignant cervical tumours, has never been reported to metastasise or lead to fatal patient outcome. We recently encountered a case of ABC that was morphologically reminiscent of prostatic differentiation, more specifically basal cell hyperplasia of the prostate. Immunohistochemistry was strongly positive for the prostate related marker NKX3.1 in the glandular cells, but there was no expression of prostate specific antigen (PSA) or prostatic acid phosphatase (PAP). However, subsequent review of five additional cervical ABCs demonstrated focal PAP expression in two of four tested cases, and all were NKX3.1 positive. NKX3.1 expression was also demonstrated in the glandular epithelium of 10 additional gynaecological lesions considered to show prostatic differentiation including five cases of cervical ectopic prostatic tissue, three ovarian teratomas with prostatic differentiation, and two vaginal tubulosquamous polyps. We suggest that some lesions traditionally classified as ABC may in fact represent a variant of prostatic differentiation within the cervix, possibly analogous to basal cell hyperplasia of the prostate.