[Pathogenesis of idiopathic interstitial pneumonia: epidemiological approach from dust theory]

In order to elucidate the factors relating to the pathogenesis of idiopathic interstitial pneumonia (IIP), an epidemiological analysis was carried out on 1880 autopsy cases of acute and chronic froms of IIP which were included in the Japanese Pathological Autopsy Records. The disease was found in a high frequency in high age groups, especially in males, and was more prevalent in agricultural than in urbanized districts of Japan. Studies on the occupational distribution demonstrated a significantly higher rate of the disease in the occupations in which workers might have been exposed to harmful dusts or fumes. Other studies on autopsy cases also reported a high incidence of IIP in occupationally exposed groups, and a clinical case control study again reported a high incidence of IIP in the occupational group including production metal workers. Together with the previous studies on element analysis of IIP tissue, exposure to harmful dusts including metallic compounds is a possible trigger, at least partly, for idiopathic interstitial pneumonia.