[Three siblings with interstitial pneumonia].

Patient 1: A 64-year-old woman was admitted for further examination after reticulonodular shadows were found on a chest X-ray film. Idiopathic interstitial pneumonia (IIP) was diagnosed. Patient 2: The 60-year-old sister of patient 1 was admitted for further examination after reticulonodular shadows were found on a chest X-ray film. IIP was diagnosed. About half a year later, her proximal interphalangeal joints had become swollen and the result of a rheumatoid hemagglutination test was positive. Therefore, the pneumonia was suspected to have been caused by a collagen-vascular disease (CVD), rheumatoid arthritis. Patient 3: The 64-year-old brother of patient 1 was examined. A chest X-ray film revealed reticulonodular shadows that were strongly suggestive of IIP. The remaining three siblings were examined. In a 62-year-old sister, the chest X-ray film was normal, but the level of anti-nuclear antigen was elevated. The fact that the level of this antigen was high in these four siblings and that the 60-year-old sister later suffered from rheumatoid arthritis suggested the presence of a factor predisposing to CVD in these siblings. The interstitial pneumonia in these siblings may have been related to CVD.