Hiroshi OIWA1, Katsuhiro OOI2, Tetsu OYAMA3, Eiji SUGYAMA2

1Department of Rheumatology, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan
2Department of Clinical Immunology and Rheumatology, Hiroshima University Hospital, Hiroshima, Japan
3Department of Rheumatology, Oyama Clinic, Hiroshima, Japan

Keywords: Antineutrophil cytoplasmic antibody; idiopathic interstitial pneumonia; microscopic polyangiitis; vasculitis


There are conflicting data to date on the causal relationship between idiopathic interstitial pneumonia and antineutrophil cytoplasmic antibody (ANCA): (1) myeloperoxidase-ANCA may play a pathogenetic role in pulmonary fibrosis, or (2) pulmonary fibrosis may induce production of the antibody. In this article, we describe a case of an elderly female patient with microscopic polyangiitis that developed after positive conversion of myeloperoxidase-ANCA during the course of idiopathic interstitial pneumonia. Our experience as well as similar case reports may suggest that idiopathic interstitial pneumonia may induce production of ANCAs and even ANCA-associated vasculitis.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Financial Disclosure

The authors received no financial support for the research and/or authorship of this article.