At low power, extensive hemorrhage is associated with the neoplastic cells. Because of their rapid growth, the tumor can outstrip their blood supply, becoming mostly necrotic and hemorrhagic with only a rim of viable tumor at the periphery.1-3
Syncytiotrophoblasts intermingle with cytotrophoblasts. The syncytiotrophoblasts are large multinucleated giant cells with an abundant amount of deeply eosinophilic cytoplasm. Cytotrophoblasts are single uniform polygonal cells with visible cytoplasmic borders and clear or pale cytoplasm. Syncytiotrophoblasts are often described as "capping" or wrapping around cytotrophoblasts.
Syncytiotrophoblasts are immunoreactive for hCG and human placental lactogen (HPL); cytotrophoblasts are weakly positive (or negative) for hCG and are negative for HPL; intermediate trophoblasts are positive for HPL and SP1 (pregnancy specific beta-1-glycoprotein).3
Choriocarcinoma is a very aggressive form of testicular cancer and carries the worst prognosis of any germ cell tumor. This same tumor can arise in the ovary (nongestational choriocarcinoma), placenta (gestational choriocarcinoma), and in the mediastinum. Like most nonseminomatous germ cell tumors, choriocarcinoma in its pure form is rare and is usually found as a component of a mixed germ cell tumor.1
Pure choriocarcinoma occurs in 2nd to 3rd decades of life and because of their small size, the tumor may not be palpable and instead, present with widespread metastases. Patients may present with hemoptysis with tumor infiltration of the lungs. These are highly aggressive tumors. 10% of patients may exhibit hormonal symptoms related to elevated hCG such as gynecomastia.2
As a point of interest, according to the LiveStrong website, Lance Armstrong's tumor was composed of 60% choriocarcinoma, 40% embryonal carcinoma and less than 1% teratoma.4
Choriocarcinoma, when part of a mixed germ cell tumor, is the component that tends to metastasize to the brain. Elevated serum hCG generally indicates a larger component of choriocarcinoma, and thus is considered an adverse prognostic factor.3
1 Kumar V, Abbas AK, Fausto N. Robbins and Cotran Pathologic Basis of Disease. 7th Ed. Philadelphia, PA: Elsevier; 2005: 1043-4.
2 Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 827-8.
3 Zhou M, Magi-Galluzzi, C. Genitourinary Pathology: Foundations in Diagnostic Pathology. Philadelphia, PA: Elvesier; 2006: 565-8.
4 LiveStrong Website at LiveStrong.org