Dermoid cysts of ovary are also known as mature cystic teratoma or benign teratomas of the ovary. This young lady in her early twenties was found to have bilateral dermoid cysts of the ovaries, although small ones at 2 to 3 cms. size.
The above ultrasound video clip shows one such case with dermoid cysts in both ovaries.
The mature cystic teratoma or dermoid cysts are seen as hyperechoic masses in the ovaries.
See: http://www.ultrasound-images.com/ovaries.htm#Ovarian_dermoid_cyst_or_Cystic_teratomas