Choriocarcinoma of the testis is a germ cell tumor that is rarely identified in its pure form; it is more often seen as a component of a nonseminomatous germ cell tumor.
Choriocarcinoma is defined by the presence of 2 cellular components, both syncytiotrophoblasts—which often show bizarre, atypical nuclei—and cytotrophoblasts, arranged in solid nests and sheets. Intermediate trophoblasts are also often present.
See the image below.
In this image, both cytotrophoblasts and syncytiotrophoblasts are admixed with rare mitotic figures identified. 100× view.
Choriocarcinoma is extremely rare in its pure form, constituting less than 1% of testicular tumors.
More frequently, this tumor is seen as a component of mixed germ cell tumors in approximately 8-10% of such cases.
The overall incidence of choriocarcinoma of the testis is approximately 0.8 cases per year per 100,000 male population in countries with the highest frequency of testicular cancer.
This tumor most is often found in males between the ages of 15 and 30 years but may be seen from puberty to old age.