Clinical stage 1 patients with a PNET component have a higher rate of relapse.
Syncytiotrophoblastic giant cells can be seen in a variety of germ cell tumors including pure seminomas, and frequently cause mild elevations of serum B-HCG. By themselves they do not alter prognosis or change the diagnosis, for example, a seminoma with syncytiotrophoblasts remains a seminoma rather than becoming a mixed seminomatous – nonseminomatous germ cell tumor; Hhwever, when present admixed with cytotrophoblasts or intermediate trophoblasts, they constitute a focus of choriocarcinoma, which is a mixed germ cell tumor.
Skeletal muscle differentiation is commonly seen in germ cell tumors. There is a distinction between the presence of skeletal muscle differentiation and a secondary somatic malignancy comprised of a sarcomatous component, namely, embryonal rhabdomyosarcoma. The latter would portray the same poor prognosis seen in choice A: PNET.
Immature glial tissue can be seen as one of the components of teratomatous tumors, and, as such does not impact prognosis.
Cytotrophoblasts are seen as a component of choriocarcinoma. Choriocarcinoma are frequently seen in the setting of a mixed germ cell tumor and oftentimes represent a small percentage of the total tumor volume. Some studies have shown that the presence of a significant component of choriocarcinoma within a mixed germ cell tumor portrays a poor prognosis, due to its propensity to disseminate throughout the body, and its strong affinity to metastasize to the central nervous system. However, it is more commonly seen in the setting of a minor component of a mixed germ cell tumor and in this setting behaves less aggressively than PNET.
