A solid mature teratoma of a feline ovary.

A 17-year-old female crossbred cat developed a mass on the left ovary. The mass was solid, firm, 5.5 x 3.5 x 4.5 cm. The mass contained ectodermal components (skin and appendages), mesodermal components (osseous, cartilaginous and adipose structures), and endodermal components (glandular structures lined by columnar epithelium). The tumor was diagnosed as a solid, mature teratoma of the ovary.