Isolated ectopic production of the free beta subunit of chorionic gonadotropin by an epidermoid carcinoma of unknown primary site.
Metastatic choriocarcinoma was suspected in a 39-year-old woman who presented 7 months postpartum with fatigue, pelvic pain, a massive pleural effusion, and a positive urine pregnancy test. Subsequent evaluation resulted in discovery of the isolated production of the free beta-subunit of chorionic gonadotropin (CG-beta) by a widespread, poorly differentiated epidermoid carcinoma. Chemotherapy was ineffective, the woman died, and at autopsy the primary site of the tumor could not be determined. The patient's serum (185 ng/ml) and a tumor metastasis (720 ng/g) contained large amounts of immunoactive material that diluted in parallel to CG-beta standard, but neither chorionic gonadotropin (CG), its alpha subunit, nor other placental proteins were detected. A monoclonal antibody that recognizes free CG-beta, but not intact CG, was instrumental in implicating an ectopic source of the CG-beta before a tissue diagnosis was obtained. When the patient's serum was chromatographed on a dextran gel, the CG-beta immunoactivity eluted in a position of higher apparent molecular weight than either standard CG or CG-beta, suggesting that this neoplasm secreted an altered molecular form of the CG-beta subunit.
D000328:Adult; D000911:Antibodies, Monoclonal; D001842:Bone and Bones / Q000000981:diagnostic imaging; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D002822:Choriocarcinoma / Q000175:diagnosis; D006063:Chorionic Gonadotropin / Q000096:biosynthesis*; D002850:Chromatography, Gel; D005260:Female; D006729:Hormones, Ectopic / Q000096:biosynthesis*; D006801:Humans; D010996:Pleural Effusion / Q000150:complications / Q000000981:diagnostic imaging; D011247:Pregnancy; D011859:Radiography; D011863:Radioimmunoassay; D011877:Radionuclide Imaging
D000911:Antibodies, Monoclonal; D006063:Chorionic Gonadotropin; D006729:Hormones, Ectopic