Tumor with >1 mature or immature somatic tissue from different germinal layers (ectoderm, mesoderm, or endoderm).
2 age peaks: <4 years old and 20's to 40's.
2nd most frequent tumor in pediatric patients, occurring as pure form.
In adults, often occur in mixed GCTs (~50%).
Gross: well-circumscribed, heterogeneous, with solid and cystic features; cysts with flaky or mucoid materials, or mature tissue with hair, cartilage, bone or teeth; fleshy or hemorrhagic foci may indicate primitive elements or non-teratomatous components.
Ectoderm: Epidermis, neuronal tissue.
Endoderm: GI or respiratory mucosa and glands.
Mesoderm: Cartilage, bone or muscles.
Undifferentiated spindle cells, primitive neuroectodermal tissue or blastemal tissue (small round blue cell).
May have with secondary malignant (somatic type) transformation (carcinoma or sarcoma).
Prepubertal teratomas are almost always benign.
Adult teratomas are considered malignant with higher recurrence or metastasis (~30%).