Spontaneous vesicular and prostatic gland epithelial squamous metaplasia, hyperplasia, and keratinized nodule...

Histopathology of the reproductive system of 76 young adult Dutch Belted and 22 young adult or adult male New Zealand White rabbits was conducted as part of fertility studies. Thirty-five (46%) of the Dutch Belted and 11 (50%) of the New Zealand White males had multifocal vesicular gland basal epithelial cell atypia and hyperplasia without metaplasia. The affected cells were taller with pale cytoplasm and a prominent basophilic nucleus longitudinally oriented and increased in number compared to more normal adjacent epithelium. Thirty-one (41%) of the Dutch Belted and 10 (45%) of the New Zealand White males showed one or more nodules of squamous metaplasia in the alveolar epithelial lining or seen occasionally within alveolar walls of the vesicular gland. The prostate was less commonly affected and none of the early cellular atypia or later cornification changes were seen. A few cornified nodules with mitotic figures resembled "carcinoma in situ," but the morphology and available biologic data supported the judgment that the lesion was benign, metaplastic, proliferative, and clinically silent.