Which testicular tumor is associated with a positive pregnancy test?

The testicular tumor that is associated with a positive pregnancy test is choriocarcinoma. This type of tumor is a type of germ cell tumor that can produce human chorionic gonadotropin (hCG), a hormone typically associated with pregnancy. The presence of hCG in the body is what leads to a positive result on a pregnancy test.

In contrast, seminoma usually does not produce hCG and is generally known for a different tumor marker, alkaline phosphatase. Teratomas may or may not produce markers and do not commonly result in a positive pregnancy test, although they can be associated with other markers. Embryonal carcinoma can produce a variety of markers but is not specifically tied to pregnancy tests like choriocarcinoma is. Thus, the clear association of choriocarcinoma with hCG makes it the correct choice in this case.