[Two cases of hypersensitivity pneumonitis due to contamination of an ultrasonic humidifier].

Two cases of hypersensitivity pneumonitis due to contamination of ultrasonic-humidifier were reported. The first case, a 64-year-old man, developed fever and dyspnea on exertion in January 1986. He was hospitalized for 18 days and received antibiotics for presumptive bacterial pneumonia. Half a day after discharge, those symptoms recurred. On readmission, fine crackles were heard at the left lung base, and chest X-ray film showed ground glass shadows all over the lung fields. Bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBLB) were performed on the next day after readmission. TBLB specimen revealed lymphocyte alveolitis, granulomatous tissue and infiltration of polymorphonuclear neutrophils (PMN) in alveoli. Differential cell count of the BAL fluid showed not only lymphocytosis (38.2%) but also increased PMNs (44.2%). In the second BAL performed 18 days later, the value of PMNs demonstrated a dramatic decrease. Environmental challenge tests revealed that his hypersensitivity pneumonitis was caused by an ultrasonic humidifier in his bed room. Immunological examinations showed positive Arthus type skin reaction and serum precipitin against Aspergillus fumigatus. Inhalation challenge with A. fumigatus produced cough and dyspnea with a decrease of 10 Torr in PaO2. These data suggest that A. fumigatus may be the causative antigen in this case. The second case, a 64-year-old man who had used ultrasonic humidifier in his living room, was admitted for 8 weeks with an illness characterized by cough, low fever and general malaise on 22 January 1987. Examination revealed fine crackles on both lung bases. Chest X-ray film demonstrated diffuse nodular shadows. The TBLB specimen showed lymphocytic alveolitis and bronchiolitis.(ABSTRACT TRUNCATED AT 250 WORDS)