Hypersensitivity pneumonitis caused by a factory humidifier. A case report

: A 64-year-old man was hospitalized for productive cough and dyspnea. Both chest radiographs and CT scans showed areas of ground-glass opacity in the middle and lower lung fields on both sides. The BAL and TBLB findings were compatible with hypersensitivity pneumonitis. The serum was negative for antibodies against Trichosporon species, and the result of a lymphocyte stimulating test for administered drugs including a Chinese medicine was also negative. A humidifier was suspected as the cause because it had been used for more than 10 years in the factory where the patient had been working. An inhalation test using the humidifier fluid successfully provoked dyspnea, fever and fine crackle, and laboratory tests demonstrated hypoxemia, reduction in vital capacity and the elevation of CRP. Agar gel diffusion using the patient's serum showed a precipitating line against Cephalosporium acremonium, but this line did not fuse with any precipitating line formed between the humidifier fluid and the serum, indicating that no Cephalosporium was Present in the humidifier fluid. Since a high level of beta-D glucan was detected in the humidifier fluid, an unidentified fungus was suspected to be the antigen.