Choriocarcinoma

A 25-year-old woman comes to the clinic due to a progressive cough accompanied by mild hemoptysis. During the past 2 weeks, she has been experiencing non-productive cough, pelvic pressure, and mild vaginal bleeding. Six weeks ago, the patient had an abortion at 15 weeks gestation, and since then, her menstrual period had not yet returned. She is in good health, and she does not smoke or use alcohol or illicit drugs. She is sexually active with her male partner and currently does not use contraception. Temperature is 37.0°C (98.6°F), pulse is 100/min, and blood pressure is 135/85 mmHg. On physical examination, the uterus is soft and mildly enlarged. Vaginal examination shows minimal blood at the vaginal vault. The cervix is closed, non-erythematous. An x-ray of the chest is obtained and shows multiple, rounded nodules of variable size scattered throughout the lungs. Which of the following findings is most specific for this patient’s conditions?