An 11-year-old girl has experienced dyspnea for the past 2 weeks. Her temperature is 37.3°C, pulse 85/minute, respiratory rate 30/minute, and blood pressure 110/60 mm Hg. On physical examination, her lung fields are clear to auscultation. Her heart rate is regular and no murmurs or gallops are heard. A chest radiograph shows prominent hilar lymphadenopathy along with a 1 cm peripheral right middle lobe nodule. No infiltrates are present. A sputum gram stain shows normal flora and routine bacterial culture reveals no pathogens. Which of the following conditions is she most likely to have?
