Is it unusual to have isolated LDH elevation and normal HCG and AFP in non-seminomatous germ cell tumor (embryonal carcinoma)?

It's hard to generalize: the details of the case matter. It is not very unusual to have an isolated LDH elevation. LDH is extremely non-specific. 101 different things can make LDH go up and this limits its usefulness as a tumor marker. Elevation of LDH on day 1 of cycle one of first-line chemotherap...

I agree completely with @Dr. First Last. After initial workup, I rarely obtain serum LDH as it is not a true "marker" like hCG and AFP. Simple things like recent trauma (or surgery), vigorous sports, or, if on chemo, even neulasta can elevate LDH. Finally, in the absence of undescended testis, scrot...