Pure choriocarcinoma is very rare and accounts for <1% of GCTs.
Usually is mixed with other GCT components (8% of mixed GCT).
May present with symptoms due to the metastatic lesions (hemoptysis, CNS symptoms) from hematogenous spread with subsequent detection of primary.
Marked elevation in serum hCG (usually >100,000 mIU/mL).
Gross: hemorrhagic nodule within the testicular parenchyma (image A); may only be a residual focus of scarring if the tumor has regressed.
Mixture of cytotrophoblasts (polygonal cells with clear cytoplasm, bland nucleus and prominent cell border) and syncitiotrophoblasts (multinucleated degenerate-appearing cells with abundant eosinophilic cytoplasm) (image B) & (image C).
Syncytiotrophoblasts wrap or cap around mononuclear cytotrophoblastic cells and form villous configuration.
Almost invariable associated with hemorrhages (search in these area).
Very rare, usually in metastatic sites; squamous-like features.
Placental site trophoblastic tumor
Very rare, composed of intermediated trophoblasts.
Immunohistochemistry: hCG+ (image D), HPL+, and glypican-3+ (only syncytiotrophoblasts).
Prognosis poorer than other GCTs, if pure.
Some patients do fairly well with chemotherapy; metastatic disease spreads hematogenously, especially to lungs, brain, and GI tract.