Here is an even larger testicular neoplasm. It is composed mostly of embryonal carcinoma, but there are scattered firmer white areas that histologically are teratoma. Thus, this testicular neoplasm is mixed embryonal carcinoma plus teratoma (sometimes called teratocarcinoma). Embryonal carcinoma is more aggressive than seminoma. The alpha-fetoprotein (AFP) in patient serum is often elevated because in such mixed germ cell tumors an element of yolk sac (endodermal sinus) tumor is present.

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