Review Question - QID 215081

A 36-year-old woman presents to her primary care physician for dyspnea, chest discomfort, and fatigue over the last 4 months. She denies any headache, vision changes, recent travel, or contact with sick people. She has trialed over-the-counter cough medicine and analgesics, which did not improve her symptoms. She has no past medical history. Her mother had a myocardial infarction at age 65 and her father is otherwise healthy. She smoked 3 cigarettes daily for 3 months but stopped over 5 years ago. Her temperature is 99°F (37.2°C), blood pressure is 125/85 mm Hg, pulse is 90/min, and respirations are 22/min with an oxygen saturation of 98% on room air. Chest auscultation is unremarkable. There is a firm and nontender lymph node in the cervical region. A radiograph of the chest is shown in Figure A. Which of the following is the most appropriate in confirming the diagnosis?