Ovary, Immature teratoma

Ovarian teratoma is an important entity for consideration in the differential diagnosis of a cystic ovarian lesion. Teratomas fall under the category of germ cell neoplasia, and are in fact the most common germ cell tumours of the ovary, typically affecting young women. Teratomas are typically comprised of elements from at least 2 of the embryonic germ cell layers (ectoderm, mesoderm, endoderm), with common elements including squamous epithelium, skin, fat, and adnexal structures – this imparts a characteristic gross appearance to these lesions, with many classically showing hair and tooth development.

Ovarian teratomas can be classified as mature or immature, with the distinction being that immature teratomas show immature/embryonal elements (which commonly are neural). The distinction is important for optimal patient management, as mature teratomas shows a benign clinical course whereas immature teratomas are considered to be malignant. In this case, the presence of immature neural elements within an otherwise classic teratoma mean that this lesion is best classified as an immature teratoma.