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A true neoplasm composed of bizarre and chaotically arranged tissues that are foreign embryologically as well as histologically to the area in which the tumor is found.



a neoplasm occurring in man and animals that results from the impaired embryonic development of tissues. Found mainly in children and adolescents, it is localized in the sex glands and occasionally in other organs and parts of the body. A teratoma generally consists of different types of tissue, including connective, epithelial, muscular, and neural tissue, and may include such differentiated derivatives of these tissues as teeth and hair.

The most complex teratomas in terms of composition and structure are those that have developed from early blastomeres or from primary sex cells that are totipotential, or able to develop into any type of body tissue. Teratomas that arise at later stages of embryonic development (after gastrulation) are limited in composition by the formative potential of the embryonic germ layer or organ from which the teratomas originate. Simple, relatively benign teratomas are distinguished from teratoblastomas— malignant tumors composed of tissues of embryonic structure and lacking a tendency to differentiate. Simple teratomas are also distinguished from teratoids—developmental defects that are not tumors but that may develop into tumors. Teratomas may become carcinomas or sarcomas.


Klinicheskaia onkologiia detskogo vozrasta. Edited by M. V. Volkov. Moscow, 1965. (Contains bibliography.)
References in periodicals archive ?
4,5) With deference to the remarkable breadth of tissues that can be present in a teratoma, these cases generally do not present diagnostic challenges; however, even with clearly teratomatous features on gross examination, immature or malignant mature components may still be present.
Germ cell neoplasms of head and neck soft tissues: a pathological spectrum of teratomatous and endodermal sinus tumours.
Extragonadal germ cell neoplasms can be classified for histopathology using mediastinal nomenclature (ie, teratomatous and nonteratomatous lesions).
Dermoid cysts may be teratomatous or non teratomatous benign malformations [3, 4, 5].
The possibility that aberrant prostatic glands represent a teratomatous component, rather than true ectopia, has also been proposed.
For example, a variegated texture including soft and firm areas and solid and cystic components can raise the possibility of a metastatic germ cell tumor with teratomatous and/or yolk sac elements arising from the gonads, retroperitoneum, mediastinum, or skull.
Other proposed theories for mucinous neoplasm involving the kidney include a possible teratomatous origin or coelomic epithelial origin because of a striking resemblance to ovarian mucinous neoplasms.
In addition, p21 nuclear immunoreactivity was seen in the differentiated teratomatous component, whereas both the intratubular embryonal carcinoma and yolk sac tumor were negative for p21.
Case report: ciliated foregut cyst of the pancreas mimicking teratomatous tumour.