Immature ovarian teratoma is an uncommon ovarian germ cell tumor, which differs from the far more common mature ovarian teratomas (dermoid cysts). Histologically they contain immature tissue, and clinically are more malignant in behavior. It is a tumor largely of young females, as in this example.

Immature teratomas may metastasize to peritoneum, liver, or lung. Large volume liver and peritoneal metastases in this case shown the soft tissue-fat-calcification typical of a dermoid.