malignant teratoma


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teratoma

 [ter″ah-to´mah]
a type of germ cell tumor made up of a number of different types of tissue from one or more of the germ cell layers; it is usually found in the ovary or testis and may be either benign or malignant.
malignant teratoma a solid, malignant ovarian tumor resembling a dermoid cyst but composed of immature embryonal or extraembryonal elements derived from all three germ layers.

immature teratoma

Adults
A teratoma with both mature elements from all 3 germ-cell layers (ectodermal, mesodermal, and endodermal), and immature (embryonic, not foetal) tissues, most commonly of neural origin, consisting of primitive neurotubules, neuroepithelial rosettes, immature glial elements, immature ependyma, primitive muscle.

Prognosis
Relatively good if under age 15; guarded if adult (see table).

Grade, Immature teratoma
I)  ≤ 1 focus/slide contains immature tissue—low-grade.
II)  2–3 foci contains immature tissue—high-grade, adjuvant radiation therapy; survival possible.
III) 4+ foci contains immature tissue—high-grade, adjuvant radiation therapy; prognosis very poor.

Based on any immature tissue on any 1 slide at 40X (low-power field).

Children
Immature teratomas behave differently in children; grading is unnecessary, the only histological predictor of recurrence is the presence of foci of yolk-sac tumour (confirmed by IHC stains for CK, AFP, glypican 3, SALL4); immature neural tissue does not indicate malignancy in immature teratomas of infants as it does in adults.

malignant teratoma

Immature teratoma, see there.

teratoma

a true neoplasm made up of a number of different types of tissue, none of which is native to the area in which it occurs; usually found in the ovary or testis. See also dermoid cyst.

malignant teratoma
a solid, malignant ovarian tumor resembling a dermoid cyst but composed of immature embryonal or extraembryonal elements derived from all three germ layers.
References in periodicals archive ?
Malignant teratoma in the thyroid gland of an adult: a case report and a review of the literature.
Malignant teratoma of the thyroid with predominantly neuroepithelial differentiation: fine needle aspiration cytologic, histologic and immunocytochemical features of a case.

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