DISTINCTIVE FEATURES

Appear in three forms. Mature (benign) teratomas (dermoid cyst), Immature (malignant) teratomas, and monodermal or specialized teratomas.

MATURE (BENIGN) TERATOMA:

Benign teratomas are bilateral in 10-15% of cases.
These tumors are cystic, are relatively small and consist of cysts lined by epidermis and adnexal structures.
The cyst may be filled with hair, sebaceous material, and teeth.
The cyst wall may contain differentiatated tissues including bone, cartilage, muscle, thyroid follicles, lining of the gastrointestinal tract, respiratory tract and other tissues.

IMMATURE (MALIGNANT) TERATOMA:

Rare tumors.
Most common in adolescents and young women.
Most of these types of tumors are malignant, grow quickly and metastasize widely.
Grossly, appear as large solid tumors with areas of necrosis and hemorrhage.
Microscopically consist of embryonic cells from one to three germ cell layers. May contain immature elements differentiating to bone, cartilage, epithelium, muscle, nerve and other tissues. The tumor is classified as grade I-III depending on the extent of the immaturity of the various elements and presence of neuroepithelium.

MONODERMAL (SPECIALIZED) TERATOMA:

The cells in these tumors grow along a single germ cell layer. Examples include struma ovarii which consists of mature thyroid tissue and ovarian carcinoid.