Lung carcinoma presenting with pathologic femur fracture and false-positive pregnancy test result.

β-Human chorionic gonadotropin (βhCG) assays are routinely used to test for pregnancy. However, βhCG may be elevated in conditions other than pregnancy. We describe a case of metastatic lung adenocarcinoma presenting with a pathologic femur fracture and a false-positive urine pregnancy test. Lung cancer is the most common nongestational malignancy that produces βhCG among reproductive-age women. Emergency physicians should consider this rare cause of a positive pregnancy test result in women who deny recent sexual intercourse, especially if the patient is older than 40 years, has a history of tobacco use, or presents with respiratory complaints.