Summer-type hypersensitivity pneumonitis. A unique disease in Japan.

A unique form of hypersensitivity pneumonitis in which clinical symptoms appear in the summer and subside spontaneously in the mid-autumn was found in Japan. This disease was named summer-type hypersensitivity pneumonitis and was found the most prevalent form in Japan. This disease has the following characteristic features: 1) initiation in the summer; 2) repeated episodes during subsequent seasons for many years; 3) familial occurrence; 4) no occupational relationship; 5) positive returning-home provocation test; 6) cough, dyspnea and remittent fever as a clinical triad; 7) diffuse nodular shadows on chest x-ray film; 8) leukocytosis with neutrophilia; 9) moderately decreased % VC and markedly decreased Dco and PaO2; 10) skin reactivity to PPD is negative while symptomatic; 11) pulmonary lesions of biopsied specimens show epithelioid cell granulomas without central necrosis (63.3 percent), plus alveolitis and/or pneumonitis; 12) isolation of patients from their home environment diminishes symptoms; 13) corticosteroid is effective; 14) seasonal atmospheric microbiological pollution is speculated upon, but the offending antigen is not defined yet.