<prompt> A middle aged man operated for testicular cancer. Histological examination shows primitive looking ugly cells with abundant mitotic cells. The tumor cells are positive for cytokeratin and CD30. The type of tumor is:Embryonal carcinomaChoriocarcinomaYolk sac tumorsTeratoma  <response>: Microscopically, embryonal carcinoma cells are the most undifferentiated of the GCT types and are characterized by alveolar or tubular architecture; pleomorphic, primitive looking ugly cells with abundant mitotic figures. Phenotypic characterization can reveal positivity for cytokeratin, CD30, PLAP, AFP, and hCG. Modest elevations of both AFP and hCG are typical, but impoantly, pure embryonal cancers can be marker-negative in the serum. Ref: Wyatt C., Butterwoh IV J.F., Moos P.J., Mackey D.C., Brown T.G. 2008. Chapter 17. Pathology of the Male and Female Reproductive Tract and Breast. In C. Wyatt, J.F. Butterwoh IV, P.J. Moos, D.C. Mackey, T.G. Brown Eds, Pathology: The Big Picture. 