Large tumor cellsNuclear OCT4 and widespread membranous KIT (or podoplanin)Absence of CD30 expressionAbsence of AFP expressionβ-hCG immunoreactivity in syncytiotrophoblastic giant cells (for the specificdiagnosis of germinoma with syncytiotrophoblastic elements)Absence of other germ cell tumor components (except syncytiotrophoblastic giantcells for the specific diagnosis of germinoma with syncytiotrophoblastic giantcells). The gene discussed is POU5F1; the disease is neoplasm.