A teratoma is a type of germ cell tumor that contains tissues derived from more than one embryonic cell layer, potentially including skin, hair, fat, bone, teeth, and even thyroid or brain tissue. In women, mature cystic teratomas (also called dermoid cysts) are the most common benign ovarian tumor. On ultrasound, an ovarian teratoma typically appears as a complex mass with a variety of echogenic features — highly echogenic areas representing fat or hair, fluid components, calcifications from teeth or bone, and sometimes the characteristic “dermoid plug” or “Rokitansky nodule” (a mural nodule within the cyst). The “tip of the iceberg” sign may be seen when strong echoes from the tumor’s contents obscure deeper structures. Teratomas can also occur in the testes, mediastinum, and sacrococcygeal region.
Sonography Term