A 12-YEAR-OLD girl was seen with dyspnea and hypoxemia at rest after being kicked by a horse on the right side of the chest. The trauma had resulted in a 15-minute loss of consciousness. Her hypoxemia resolved with the administration of supplemental oxygen, and results of an initial chest radiograph were obtained within 2 hours of the trauma (Figure 1). Findings on a subsequent radiograph 2 days later were unchanged, and a computed tomographic scan of the chest was performed (Figure 2).
Her respiratory history was remarkable for a few episodes of wheezing that she had experienced as an infant. She denied recent fever, cough, shortness of breath, chest pain, or hemoptysis. Findings from a physical examination, performed 3 days after the trauma, revealed a well-developed, well-nourished girl in no distress. Her respiratory rate was 20/min. No adventitial breath sounds were auscultated. Tuberculin skin test (purified protein derivative) results and