Yolk Sac Tumor (endodermal sinus tumor)
General: Also classified as a nonseminomatous germ cell tumor, is seen in two distinct circumstances:
- Isolated/pure: Organoid appearance, seen in infants & children (less than 2 years), associated with excellent prognosis.
- Component of mixed germ cell tumor: Less differentiated, more malignant morphology and prognosis similar to that of embryonal carcinoma.
Gross:
Microscopic: Differentiation towards extraembryonic endoderm and mesoderm. Typically recognized by intermingling of epithelial and mesnchymal elements in an organoid fashion. Perivascular Schiller-Duval bodies are considered very distinctive. Hyaline intracytoplasmic and extracytoplasmic round inclusions/globules (eosinophilic, PAS positive and diastase resistant) are also distinctive.
Differential Diagnosis:
Stains:
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Cases:
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