Teratomas are unusual forms of cancer in that they are composed of tissues such as tooth and bone, tissues not normally found in the organ in which the tumor appears.

惭愧，这句话什么意思都想不通，那位大虾帮帮手？

Teratomas是一种异常的cancer形式, 因为它们(Teratomas)是由一些组织组成,例如牙齿和骨头,这些组织不经常在肿瘤出现的组织里被发现.