Dentigerous Equine Teratoma in a Stallion: Surgical Management and Clinicopathology.

Teratoma is a rare germ cell testicular cancer composed of cells that are not normally present in the site where it originates. These tumors are rarely described in horses, where they may develop due to cryptorchidism. Teratomas consist of cells originating from different germinal layers, arising from germinal multi-potential cells with differentiation defects, and can simultaneously contain several tissues from two or more embryonic layers. Testicular teratomas are described in horses, cats, dogs, wild boars, bulls, and humans. In the rare descriptions found in literature of testicular teratoma in stallions, they occur frequently in cryptorchid testicles, as a consequence of congenital neoplasm. To our knowledge there is no other report of a dentigerous equine teratoma in a stallion. We describe here a successful laparoscopic removal of a testicular teratoma and its clinic-pathological features.