Which type of ovarian tumor is associated with elevated levels of alpha-fetoprotein (AFP)?

The association of elevated levels of alpha-fetoprotein (AFP) with certain types of ovarian tumors is primarily seen in germ cell tumors. Germ cell tumors can be divided into several subtypes, and one of the most notable characteristics of some of these tumors, particularly non-seminomatous germ cell tumors such as yolk sac tumors, is the production of AFP. Elevated AFP levels can indicate the presence of these tumors and serve as a useful biomarker during diagnosis and monitoring.

In the context of the other options, serous cystadenomas typically do not produce AFP and are more commonly associated with other markers, while granulosa cell tumors are derived from sex-cord stromal cells and primarily produce estrogen rather than AFP. Teratomas, which are a subtype of germ cell tumors, may contain various tissue types but are not consistently associated with increased AFP unless they have specific features that resemble a yolk sac tumor. Thus, the connection between germ cell tumors and elevated AFP levels is a crucial factor in understanding this aspect of ovarian tumors.