American Urological Association - Teratoma
- 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.
- Mature teratoma
- Ectoderm: Epidermis, neuronal tissue.
- Endoderm: GI or respiratory mucosa and glands.
- Mesoderm: Cartilage, bone or muscles.
- Immature teratoma
- 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%).