Yolk sac tumor → AFP. Choriocarcinoma → β-hCG, often very high. Embryonal carcinoma → either or both. Across nonseminomatous GCTs, AFP and/or β-hCG up in ~85%.
Pure seminoma: AFP normal almost always; β-hCG up only in a minority. If AFP is elevated, it is not a pure seminoma.
Marker source: AFP from yolk sac (endodermal) elements; β-hCG from syncytiotrophoblast. Those two facts organize all the subtypes.
I've been turning my UWorld biochem set into notes and flashcards, and this mapping finally made the subtypes stick. How do you keep the GCT marker map straight?
Credit: Hellerhoff, Wikimedia Commons, CC BY-SA 4.0
#USMLE #Step1 #Oncology #Pathology
What I like: the two markers tell you which cells are inside. Anterior mediastinum by the 4 T's: thymoma, teratoma (and other germ cell tumors), "terrible" lymphoma, thyroid.
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.
