Abstract

Division of Respiratory Medicine, Hiratsuka Kyosai Hospital, Kanagawa, Japan A 51-year-old man who had been working for 10 years with polyurethane paint containing isocyanate (MDI) was admitted to our hospital with complaints of fever and exertional dyspnea. Fine crackles were heard in both bases, and the patient had clubbed fingers. A chest X-ray film and computed tomograms of the lungs revealed patchy infiltrative shadows in both lung fields and subpleural honeycombing associated with irregular linear areas. Examination of bronchoalveolar lavage fluid showed increased T lymphocytes and a decreased CD 4/8 ratio. Specimens obtained by transbronchial lung biopsy revealed lymphoplasmacytic infiltration into the thickened alveolar walls, macrophage accumulation, and micro-epithelioid cell granulomas in the alveolar sacs. Hypersensitivity pneumonitis was suspected although the causative antigen was not identified because the results of short-term environmental provocation tests were negative in the patient's home and workplace. After discharge, the patient continued working as a paint sprayer. His acute symptoms recurred 1 month after exposure to isocyanate. Similar episodes occurred on two separate occasions. In addition, the patient tested positive for antibody to MDI-HSA in bronchoalveolar fluid. From the above observations, the patient was given a diagnosis of chronic hypersensitivity pneumonitis due to isocyanate (MDI). This condition is extremely rare. Furthermore, it is interesting that acute symptoms recurred 1 month after environmental exposure to the causative antigen

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