A non-germinomatous germ cell tumor characterized by the presence of various tissues which correspond to the different germinal layers (endoderm, mesoderm, and ectoderm). It occurs in the testis, ovary, and extragonadal sites including central nervous system, mediastinum, lung, and stomach. According to the level of differentiation of the tissues which comprise the tumor, teratomas are classified as mature or immature. Mature teratomas are composed of well differentiated, adult-type tissues. Immature teratomas are composed of immature, fetal-type tissues.

A non-seminomatous germ cell tumor characterized by the presence of various tissues which correspond to the different germinal layers (endoderm, mesoderm, and ectoderm). It occurs in the testis, ovary, and extragonadal sites including central nervous system, mediastinum, lung, and stomach. According to the level of differentiation of the tissues which comprise the tumor, teratomas are classified as benign (grade 0 or 1), immature (grade 2), and malignant (grade 3). Grade 0 teratomas contain only mature elements; grade 1 teratomas have a limited degree of immaturity; grade 2 teratomas have a more extensive degree of immaturity; grade 3 teratomas are composed exclusively of immature tissues. The prognosis depends on patient age, tumor size and grade, and stage.

A true neoplasm composed of a number of different types of tissue, none of which is native to the area in which it occurs. It is composed of tissues that are derived from three germinal layers, the endoderm, mesoderm, and ectoderm. They are classified histologically as mature (benign) or immature (malignant). (From DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1642)

A type of germ cell tumor that may contain several different types of tissue, such as hair, muscle, and bone. Teratomas occur most often in the ovaries in women, the testicles in men, and the tailbone in children. Not all teratomas are malignant.

The presence of a teratoma.

True neoplasm composed of a number of different types of tissue, none of which is native to the area in which it occurs; composed of tissues that are derived from three germinal layers, the endoderm, mesoderm, and ectoderm; may be solid or cystic and are classified histologically as mature, immature, and malignant.