Marker source: AFP from yolk sac (endodermal) elements; β-hCG from syncytiotrophoblast. Those two facts organize all the subtypes.
Sharing a case. 31-year-old man: a month of cough, chest discomfort, exertional dyspnea, plus 4.5 kg weight loss. CT: large anterior mediastinal mass. Labs: AFP and β-hCG both up. Answer: nonseminomatous germ cell tumor.