Third-Trimester Intraplacental Choriocarcinoma Presenting With Respiratory Failure and Hyperthyroidism

ABSTRACT Objective: Choriocarcinoma is an aggressive disease typically identified after a molar pregnancy. Diagnosis with a co-existing pregnancy is extremely rare. Only 35 cases have been reported from 1907 to 1995. We report a case of choriocarcinoma diagnosed during the third trimester of an intra-uterine pregnancy presenting with respiratory failure and biochemical hyperthyroidism. Methods: This is a case report of an intraplacental choriocarcinoma during the third trimester of pregnancy. We included a review of literature highlighting the rarity of this disease, diagnostic challenges, and treatment options. Results: A 34-year-old woman, 31 weeks pregnant, presented with dyspnea and hemoptysis for 2 weeks. Imaging showed bilateral pulmonary infiltrates, suggestive of pneumonia. Thyroid function tests checked due to tachycardia revealed hyperthyroidism, with thyroid-stimulating hormone of 0.02 μIU/mL (normal range, 0.5 to 4.5 μIU/mL) and free thyroxine of 4.8 ng/dL (normal range, 0.7 to 1.8 ng/dL). Serum human chorionic gonadotropin was elevated, at 1,433,740 mIU/mL. Respiratory failure ensued, requiring ventilatory support. Emergent cesarean section was done due to worsening clinical status. Histopathologic findings of the placenta were diagnostic of intraplacental choriocarcinoma. Chemotherapy was given; however, the patient developed acute cerebral hemorrhage and she eventually expired. Conclusion: Diagnosis of choriocarcinoma co-existing with intra-uterine pregnancy can be difficult, as initial symptoms can be mistaken for other diseases, such as pneumonia in this case. Biochemical hyperthyroidism during the third trimester in a patient with no history of thyroid disease is rare, and choriocarcinoma should be considered. A timely diagnosis is imperative, as early intervention with chemotherapy can be curative and potentially life-saving. Abbreviations: FIGO = International Federation of Gynecology and Obstetrics GTN = gestational throphoblastic neoplasia hCG = human chorionic gonadotropin T4 = free thyroxine TSH = thyroid-stimulating hormone WHO = World Health Organization