Presence of more than two germ cell layer in a tumor is called :
**Core Concept**
Tumors are classified based on their cellular origin and differentiation. The germ cell layer is one of the three primary germ layers formed during embryonic development: ectoderm, endoderm, and mesoderm. A tumor composed of more than two germ cell layers is an example of a teratoma, which arises from the abnormal development and proliferation of cells from multiple germ layers.
**Why the Correct Answer is Right**
Teratomas are a type of germ cell tumor that contains tissue from all three germ layers, which can include ectodermal, endodermal, and mesodermal components. This is in contrast to other types of germ cell tumors that are composed of cells from a single germ layer, such as yolk sac tumors (endodermal sinus tumors) or embryonal carcinomas. The presence of multiple germ layers in a tumor is a hallmark of teratomas, which can be benign or malignant.
**Why Each Wrong Option is Incorrect**
* **Option A:** Not relevant to the classification of tumors based on germ cell layers.
* **Option B:** Refers to a type of tumor that arises from the neural crest, which is a group of cells that give rise to the peripheral nervous system and other structures.
* **Option C:** Refers to a type of tumor that arises from the epithelial cells of the skin or other organs, but does not specifically relate to the presence of multiple germ cell layers.
**Clinical Pearl / High-Yield Fact**
Teratomas can contain a wide range of tissues, including hair, muscle, bone, and teeth, which can make them difficult to diagnose and treat.
**Correct Answer:** C.