Equine antral follicle containing cartilage and bone: ovarian teratoma

A teratoma is a tumor characterized by a change in the size of the ovary and by presence of well differentiated tissues that are not usual to ovarian stroma. This entity is derived from totipotent cells and early ovarian germ cell differentiation into various tissues. This report aims to describe the morphologic and histologic features of a teratoma found within an antral follicle in the ovary of a mare after slaughter. The ovary was 8 cm in diameter and had a smooth, nodular surface. One antral follicle of 4 cm in diameter containing fluid and lumps of material, both yellow in color, and adhering to a skin, cartilage and bone fragment 1 cm in diameter was visually identified to be attached to the ovarian tissue. Healthy follicles smaller than 3 cm in diameter and hemorrhagic follicle were also observed. Histologic showed normal ovarian tissue containing antral follicles, hemorrhagic follicles and neoformation of multiple tissues. The presence of areas containing epidermis, dermis and skin appendages (sebaceous glands, sweat glands and hair follicles) surrounding cystic cavities filled with keratin, fragments of the cholesterol crystal, and macrophage-containing, waxy sebaceous material was also noted. This paper reports the presence of a teratoma within an equine antral follicle and suggests functionality of the ovary, even in the presence of the teratoma, due to the presence ofactive antral follicles and recent ovulation.