Development of microscopic polyangiitis-related pulmonary fibrosis in a patient with autoimmune pulmonary alveolar proteinosis

Case report

Yuhei Kinehara¹, Hiroshi Kida^1*, Yoshikazu Inoue², Masaki Hirose², Akihiko Nakabayashi¹, Yoshiko Takeuchi¹, Yoshitomo Hayama¹, Kiyoharu Fukushima¹, Haruhiko Hirata¹, Koji Inoue¹, Toshiyuki Minami¹, Izumi Nagatomo¹, Yoshito Takeda¹, Toshiki Funakoshi³, Takashi Kijima¹ and Atsushi Kumanogoh¹

• *Corresponding author: Hiroshi Kida hiroshi.kida@imed3.med.osaka-u.ac.jp

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BMC Pulmonary Medicine 2014, 14:172  doi:10.1186/1471-2466-14-172

Published: 4 November 2014

Abstract

Background

Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare lung disease caused by the autoantibody against granulocyte-macrophage colony stimulating factor (GM-CSF). The clinical course of aPAP is variable; in severe cases, patients develop lethal respiratory failure due to pulmonary fibrosis. However, the pathogenesis of pulmonary fibrosis in aPAP has never been delineated.

Case presentation

Here, we describe a rare case of aPAP that was subsequently complicated by microscopic polyangiitis-related pulmonary fibrosis. The patient was a 75-year-old Japanese man diagnosed with aPAP based on the crazy-paving appearance on high-resolution computed tomography (HRCT), “milky” appearance of broncho-alveolar lavage fluid (BALF), and elevated serum levels of the anti-GM-CSF antibody. The patient was followed-up without aPAP-specific treatment for 3 years. During this period, both hematuria and proteinuria appeared; in addition, serum myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA) turned positive and increased markedly. The second BAL performed one year after the diagnosis, showed that the “milky” appearance had resolved. The HRCT showed that fibrotic changes had developed and that the crazy-paving appearance had disappeared. These data suggest an association between pulmonary fibrosis that developed during the natural course of aPAP and ANCA-related systemic vasculitis.

Conclusion

This is the first case report that suggests the existence of a pathogenetic relationship between ANCA-associated systemic vasculitis and aPAP-related pulmonary fibrosis. The link between ANCA-associated systemic vasculitis and aPAP-related pulmonary fibrosis requires further investigation.

Keywords: 

Pulmonary alveolar proteinosis; Pulmonary fibrosis; Myeloperoxidase antineutrophil cytoplasmic antibody 

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