C. Ectopic prostate glands with squamous metaplasia

Histology: Typical large benign endocervical glands are noted with abundant eosinophilic cytoplasm and a single layer of simple round basally situated nuclei. Adjacent to these glands are smaller more variably sized glands with squamous metaplasia, some of which appears immature and other areas with abundant clear cytoplasm typical of glycogenated squamous metaplasia. At the periphery of these small glands, the cells are low cuboidal with pale cytoplasm and in areas what appeared to be a basal cell layer beneath the overlying cuboidal cells. Some of the cells had a mixture of red-orange and purple cytoplasmic granules consistent with lipofuscin pigment.

Discussion: The glands with squamous metaplasia differ from the adjacent endocervical glands in term of the size, shape, nature of their cytoplasm, and lack of a basal cell layer. If one mentally subtracts the squamous metaplasia, the glands are typical benign prostate glands. Immunohistochemistry was performed showing focal cytoplasmic and luminal staining in the glandular lining diagnostic of ectopic prostate glands with squamous metaplasia. There have been a few cases of ectopic prostate tissue involving the cervix. Possible theories of histogenesis include a developmental anomaly, metaplasia of preexisting endocervical glands, and derivation from mesonephric remnants. Squamous metaplasia of ectopic prostate tissue in the cervix is common and reflects the effect of endogenous female estrogen on the prostate, analogous to what would be seen in the native prostate with exogenous estrogen given to male patients.

Ectopic Prostatic Tissue in the Uterine Cervix and Vagina Report of a Series With a Detailed Immunohistochemical Analysis. Am J Surg Pathol 2006;30:209–215