Incidence of myeloperoxidase anti-neutrophil cytoplasmic antibody positivity and microscopic polyangitis in the course of idiopathic pulmonary fibrosis

Respir Med. 2013 Apr;107(4):608-15. doi: 10.1016/j.rmed.2013.01.006. Epub 2013 Feb 19.


Background: Pulmonary fibrosis is a manifestation of microscopic polyangitis (MPA), and often precedes the detection of MPA. The prevalence and sequence of myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) and MPA in patients initially diagnosed with idiopathic pulmonary fibrosis (IPF) have not been precisely elucidated.

Methods: We enrolled 61 consecutive patients with IPF and measured the MPO-ANCA titers at initial presentation and during the follow-up period. Clinical, radiologic and histologic features of MPO-ANCA-positive cases were examined.

Results: Of 61 patients, 3 (4.9%) had positive MPO-ANCA titers at the initial presentation of IPF. During the disease course, MPO-ANCA-positive conversion occurred in 6 patients and the prevalence of ANCA increased to 14.8%. Among the nine patients positive for MPO-ANCA, two patients developed MPA during follow-up. Histologic features of MPO-ANCA-positive pulmonary fibrosis were compatible with the usual interstitial pneumonia pattern in which alveolar hemorrhage and capillaritis were not observed. The patients with MPO-ANCA-positive conversion showed increased percentages of bronchoalveolar lavage eosinophils and more frequent complication of pulmonary emphysema compared to those with MPO-ANCA-negative IPF.

Conclusions: The findings of the present study demonstrated that patients with an initial diagnosis of IPF occasionally acquire MPO-ANCA, which develops to MPA during the disease course of IPF. The presence of pulmonary eosinophilia and low attenuation areas on computed tomography scans might be predictive of MPO-ANCA positive conversion.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Antineutrophil Cytoplasmic / blood*
  • Bronchoalveolar Lavage Fluid / cytology
  • Female
  • Follow-Up Studies
  • Glucocorticoids / therapeutic use
  • Humans
  • Idiopathic Pulmonary Fibrosis / complications
  • Idiopathic Pulmonary Fibrosis / diagnostic imaging
  • Idiopathic Pulmonary Fibrosis / drug therapy
  • Idiopathic Pulmonary Fibrosis / immunology*
  • Immunosuppressive Agents / therapeutic use
  • Male
  • Microscopic Polyangiitis / diagnostic imaging
  • Microscopic Polyangiitis / drug therapy
  • Microscopic Polyangiitis / etiology
  • Microscopic Polyangiitis / immunology*
  • Middle Aged
  • Peroxidase / immunology*
  • Tomography, X-Ray Computed
  • Treatment Outcome


  • Antibodies, Antineutrophil Cytoplasmic
  • Glucocorticoids
  • Immunosuppressive Agents
  • Peroxidase