Severe hypoxemia in farmer's lung disease with normal findings on chest roentgenogram

A 33-year-old woman farmer developed an acute episode of fever, cough, and shaking chills with persistent shortness of breath. Her PaO2 was 51 with a restrictive pattern on pulmonary function. Her diffusion capacity was 36 percent of predicted. In spite of these abnormalities, she always had normal chest roentgenographic findings. Further studies, including a lung biopsy, led to the diagnosis of farmer's lung disease.