What are yolk sac tumors?

➢ Most common primary testicular neoplasm in children younger than 3 years of age ➢ In this age group, it has a very good prognosis ➢ In adults, yolk sac tumors most often are seen admixed with embryonal carcinoma ➢ Large and may be well demarcated ➢ Low cuboidal to columnar epithelial cells that form microcysts, lacelike (reticular) patterns, sheets, glands, and papillae ➢ A distinctive feature is the presence of structures resembling primitive glomeruli called schiller-duval bodies ➢ Often have eosinophilic hyaline globules containing α1-antitrypsin and alpha fetoprotein (AFP), which can be demonstrated by immunohistochemical techniques