Extragestational βHCG secretion due to an isolated lung epithelioid trophoblastic tumor: microsatellite genotyping of tumoral cells confirmed their placental origin and oriented specific chemotherapy.

CONTEXT: Persistent secretion of β-human chorionic gonadotropin (βHCG) in the absence of an ongoing or recent pregnancy and without persistent uterine gestational disease is a rare but challenging situation that requires locating the extrauterine secreting tumor and distinguishing between extragestational choriocarcinoma and gestational trophoblastic neoplasms.

CASE PRESENTATION: An unexplained, persistent extragestational βHCG secretion occurring in a 29-year-old, nonsmoking woman with abnormal uterine bleeding 4 years after a normal pregnancy and without persistent gestational disease led to the discovery by whole-body computed tomography/positron emission tomography of an isolated pulmonary tumor.

OBJECTIVE

Characterization of paternal alleles in tumoral cells in order to establish their fetal origin, which may be helpful for the diagnosis and treatment of such tumors.

METHODS AND

RESULTS

After the surgical procedure, clinical, histological, and immunocytochemical analysis ruled out primary or metastatic bronchopulmonary carcinoma or choriocarcinoma and supported the diagnosis of an isolated, primary, epithelioid trophoblastic tumor. Microsatellite genotyping of tumoral cells identifying paternal alleles confirmed their placental origin and their migration to the lungs, with likely secondary malignant transformation, and guided the choice of postsurgical chemotherapy needed to completely eradicate βHCG secretion.

CONCLUSION

Persistent extragestational secretion of βHCG in a young nonsmoking woman with a precedent pregnancy and an isolated lung tumor suggests the diagnosis of epithelioid trophoblastic tumor, a very rare malignant tumor for which placental origin needs to be confirmed, especially when occurring several years after the patient's last pregnancy. Simple microsatellite genotyping of tumoral cells will allow this confirmation of diagnosis and help in personalizing chemotherapy.