title: Incidence of myeloperoxidase anti-neutrophil cytoplasmic antibody positivity and microscopic polyangitis in the course of idiopathic pulmonary fibrosis.
abstract: 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.
authors: Department of Internal Medicine 3, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama-machi, Yufu-shi, Oita 879-5593, Japan. mando@oita-u.ac.jp
authors: Masaru
authors: M
authors: Ando
authors: Eishi
authors: E
authors: Miyazaki
authors: Toshihiro
authors: T
authors: Ishii
authors: Yutaka
authors: Y
authors: Mukai
authors: Mari
authors: M
authors: Yamasue
authors: Hideaki
authors: H
authors: Fujisaki
authors: Takeo
authors: T
authors: Ito
authors: Shin-ichi
authors: S
authors: Nureki
authors: Toshihide
authors: T
authors: Kumamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D005260:Female; D005500:Follow-Up Studies; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000276:immunology*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D055953:Microscopic Polyangiitis / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000209:etiology / Q000276:immunology*; D008875:Middle Aged; D009195:Peroxidase / Q000276:immunology*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D005938:Glucocorticoids; D007166:Immunosuppressive Agents; D009195:Peroxidase