title: Interstitial pneumonia associated with MPO-ANCA: clinicopathological features of nine patients.
abstract: Myeloperoxidase anti-neutrophil cytoplasmic autoantibody (MPO-ANCA) is a well known marker for small vessel vasculitis. Recent reports have demonstrated that interstitial pneumonia (IP) may rarely be associated with serum MPO-ANCA. Yet, little is known about the histological features. We reviewed surgical lung biopsy from nine patients with IP of uncertain etiology with serum MPO-ANCA. There was a male predominance (6:3) with a median age of 62.1. Histologically, eight patients presented with a usual interstitial pneumonia (UIP) pattern of pulmonary fibrosis, frequently accompanied by areas of nonspecific interstitial pneumonia (NSIP) pattern. One patient showed diffuse alveolar damage (DAD), and two patients showed mixture of UIP and DAD reflecting acute exacerbation of UIP. Microscopic honeycomb cysts were common, but fibroblastic foci were inconspicuous. The most frequent additional findings were small airway disease (9/9), and lymphoid follicles (7/9). Neither capillaritis nor vasculitis was seen in any of our cases. Three patients had microscopic hematuria, but none progressed to microscopic polyangiitis during the follow up. Mortality rate was 44% (median follow up 39.1 months). IP associated with MPO-ANCA showed characteristic histology dominated by UIP pattern. Vasculitis was not identified in our cohort, but small airways disease and lymphoid follicles were present in most cases. IP associated with MPO-ANCA may be a histologically distinctive disease from idiopathic pulmonary fibrosis. Mortality was relatively high and life threatening acute exacerbation may occur.
authors.affiliation: Laboratory of Pathology, Toyama University Hospital, Toyama, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tanaka
authors.forename: Kyoko
authors.initials: K
authors.lastname: Otani
authors.forename: Ryoko
authors.initials: R
authors.lastname: Egashira
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kashima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Taniguchi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kondoh
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kataoka
authors.forename: Akira
authors.initials: A
authors.lastname: Shiraki
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kitasato
authors.forename: Kevin O
authors.initials: KO
authors.lastname: Leslie
authors.forename: Junya
authors.initials: J
authors.lastname: Fukuoka
mesh_terms: D000368:Aged; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000378:metabolism*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D017563:Lung Diseases, Interstitial / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009195:Peroxidase / Q000276:immunology*; D011379:Prognosis
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D009195:Peroxidase