[A case of rheumatoid lung exacerbated by acetaminophen-induced pneumonitis].

A 57-year-old man was admitted with a high fever, dry cough, severe dyspnea and an interstitial shadow bilaterally on chest roentogenogram. Although his illness was not diagnosed, he was treated with a high dose of methylprednisolone (1 g/day for 3 days) for acute interstitial lung disease. As the 3-day treatment was not effective, high-dose methylprednisolone therapy was repeated. Subsequently, he was treated with prednisolone (60 mg/day), after which his condition improved. After 8 months, the patient caught cold for which he was treated. Subsequently his previous lung disease appeared again. His illness, improved after steroid therapy. The patient had been treated with Shin-Ruru-A tablets during his first admission. A lymphocyte stimulation test for Shin-Ruru-A-Tablet, PL granule, and acetaminophen (which is the common constituent of the former two drugs), was positive. Polyarthralgia, bone lesions joint swelling, and a positive rheumatoid factor test were present on first admission. Therefore, his illness was diagnosed as rheumatoid arthritis (RA). As the interstitial shadow remained after treatment of the lung disease, a thoracoscopic lung biopsy was performed. The specimen revealed an intensive lymphocytic infiltration, perivasculatitis, and thickening of the alveolar septa. These findings corresponded with those of lung disease associated with RA. The results suggest that lung disease associated with collagen vascular diseases may be exacerbated by drug-induced pneumonitis.