Home Education AUAUniversity Education Products & Resources Pathology for Urologists Testis Germ Cell Tumors Teratoma


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  • 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.

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  • 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%).