title: Pulmonary alveolar proteinosis-like change: A fairly common reaction associated with the severity of idiopathic pulmonary fibrosis.
abstract: BACKGROUND
  We have seen cases of chronic interstitial pneumonia (IP) with pulmonary alveolar proteinosis (PAP)-like changes that are focal histological features similar to PAP. To our knowledge, the association between PAP-like changes and chronic IP has not been investigated. We aimed to evaluate the incidence of PAP-like changes in chronic IP cases, and the association between the existence of PAP-like changes and the clinical features seen in patients with idiopathic pulmonary fibrosis (IPF).
  
  
  METHODS
  We selected 144 cases of chronic IP that had a video-assisted thoracoscopic surgery biopsy between 2008 and 2011. Clinical records and hematoxylin and eosin-stained slides were reviewed, and clinicopathological findings, including the cumulative survival probability, were compared between IPF cases with and without a PAP-like change.
  
  
  RESULTS
  A PAP-like change was identified in 20 of 144 cases (13.9%) of chronic IP and 14 of 61 IPF cases (23.0%). When comparing IPF cases with and without a PAP-like change, histological findings of honeycomb cysts and fibroblastic foci were associated with PAP-like changes (p=0.022 and 0.036, respectively). The percent-predicted values for forced vital capacity and diffusion capacity of carbon monoxide were lower (p=0.006 and 0.015, respectively), and concentrations of serum Krebs von den Lungen-6 and lactate dehydrogenase were higher (p=0.007 and 0.037, respectively) in cases of IPF with a PAP-like change than in those without one.
  
  
  CONCLUSIONS
  The presence of a PAP-like change in IPF cases was fairly common in our study, and may be a secondary reaction associated with IPF severity.
authors.affiliation: Laboratory of Pathology, Toyama Thoracic Society, Toyama University Hospital, Sugitani, Toyama 930-0152, Japan. Electronic address: bb55313028@cc.nagasaki-u.ac.jp.
authors.forename: Sayuri
authors.initials: S
authors.lastname: Nunomura
authors.affiliation: Laboratory of Pathology, Toyama Thoracic Society, Toyama University Hospital, Sugitani, Toyama 930-0152, Japan. Electronic address: tanaka.t.tomonori@gmail.com.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Pathology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan. Electronic address: toshi-n@med.uoeh-u.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nakayama
authors.affiliation: Laboratory of Pathology, Toyama Thoracic Society, Toyama University Hospital, Sugitani, Toyama 930-0152, Japan. Electronic address: o.kyoko303@gmail.com.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Otani
authors.affiliation: Department of Respiratory Medicine, Kyorin University, School of Medicine, 6-20-2 Niikawa, Mitaka-shi, Tokyo 181-8611, Japan. Electronic address: h141@ks.kyorin-u.ac.jp.
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Ishii
authors.affiliation: Laboratory of Pathology, Toyama Thoracic Society, Toyama University Hospital, Sugitani, Toyama 930-0152, Japan. Electronic address: t-kaz@nagasaki-u.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tabata
authors.affiliation: Department of Respiratory Medicine and Allergy, Tosei General Hospital, Nishioiwake-cho, Seto, Aichi 489-8642, Japan. Electronic address: konyasu2003@yahoo.co.jp.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kondoh
authors.affiliation: Department of Respiratory Medicine and Allergy, Tosei General Hospital, Nishioiwake-cho, Seto, Aichi 489-8642, Japan. Electronic address: kataoka@tosei.or.jp.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kataoka
authors.affiliation: Department of Radiology, Kinki Central Hospital of Mutual Aid Association of Public School Teachers, 3-1 Kurumazuka, Itami-shi, Hyogo 664-8533, Japan. Electronic address: Johkoht@aol.com.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Johkoh
authors.affiliation: Department of Respiratory Medicine and Allergy, Tosei General Hospital, Nishioiwake-cho, Seto, Aichi 489-8642, Japan. Electronic address: hiro-tosei-lung@kkd.biglobe.ne.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Taniguchi
authors.affiliation: Department of Pathology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan. Electronic address: fukuokaj@nagasaki-u.ac.jp.
authors.forename: Junya
authors.initials: J
authors.lastname: Fukuoka
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011649:Pulmonary Alveolar Proteinosis / Q000473:pathology*; D011658:Pulmonary Fibrosis / Q000473:pathology*
keywords: Honeycomb cyst; Idiopathic pulmonary fibrosis; KL-6; Pulmonary alveolar proteinosis