- Circumscribed tumor with invasive and destructive growth pattern.
- Sheets and strands of mononuclear cuboidal cells with occasional multinucleated syncytiotrophoblastic cells in a necrotic background. Multinucleated syncytiotrophoblastic cells stain positive for hCG.
- Tumor infiltrates into lymph- and blood vessels.
- Apart from the tumor testicular atrophy.
- Presentation with painless enlargement of the testis.
- Patients with choriocarcinoma always exhibit elevated serum levels of hCG.
- Extensive hematogenous metastasis into lung, liver, but also brain, kidneys and bone marrow.
- Choriocarcinomas respond well to chemotherapy.
In females non-gestational and gestational choriocarcinomas are distinguished. The latter are observed more frequently, the incidence being about 1:24000 pregnancies. Of those, roughly 50% are derived from complete hydatiform moles, around 25% follow normal pregnancies and another 25% spontaneous abortion.