title: Restrictive allograft syndrome and idiopathic pleuroparenchymal fibroelastosis: do they really have the same histology?
abstract: OBJECTIVE
  Restrictive allograft syndrome (RAS) and idiopathic pleuroparenchymal fibroelastosis (IPPFE) are two different diseases reported to share the same histology. RAS relates to chronic allograft dysfunction in lung transplantation, with IPPFE being a rare condition in native lungs. Our aim is to compare their histologies alongside biopsies of usual interstitial pneumonia (UIP), to determine if there are differences that might help to elucidate the pathogenesis.
  
  
  RESULTS
  We selected four postmortem allograft lungs from patients who developed a clear clinical RAS pattern, five biopsies diagnosed as IPPFE, five UIP biopsies and five sections of normal lung. Histopathological features were described without knowledge of clinical and radiological features. Both RAS allografts and IPPFE biopsies showed intra-alveolar fibrosis and elastosis (IAFE), but RAS allografts also showed concomitant obliterative bronchiolitis, vascular lymphoplasmacytic inflammation within fibrointimal thickening, less fibroblastic foci (FF) at the advancing edge of the fibrosis (one against 14.4 FF in 2 mm2) and a slight reduction of the capillary network compared to UIP (P = 0.07) and controls (P = 0.06). The main differences seen in UIP were the lack of IAFE and the presence of honeycomb change.
  
  
  CONCLUSIONS
  RAS and PPFE histopathology both show IAFE, but display various differences, particularly in their vascular morphology that may allow further understanding of pathogenesis.
authors.affiliation: Histopathology Department, Royal Brompton and Harefield NHS Foundation Trust, London, UK.|Biomedical Respiratory Unit, Imperial College London, London, UK.
authors.forename: Maria A
authors.identifier: http://orcid.org/0000-0002-9454-2091
authors.initials: MA
authors.lastname: Montero
authors.affiliation: Biomedical Respiratory Unit, Imperial College London, London, UK.
authors.forename: Tina
authors.initials: T
authors.lastname: Osadolor
authors.affiliation: Histopathology Department, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Reena
authors.initials: R
authors.lastname: Khiroya
authors.affiliation: Histopathology Department, Vall d'Hebron University Hospitals, Barcelona, Spain.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Salcedo
authors.affiliation: Histopathology Department, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Jan L
authors.initials: JL
authors.lastname: Robertus
authors.affiliation: Histopathology Department, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rice
authors.affiliation: Histopathology Department, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Nicholson
authors.affiliation: Respiratory Medicine, Vall d'Hebron University Hospitals, Barcelona, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Roman
authors.affiliation: Respiratory Medicine, Vall d'Hebron University Hospitals, Barcelona, Spain.
authors.forename: Victor
authors.initials: V
authors.lastname: Monforte
mesh_terms: D064591:Allografts / Q000473:pathology; D004547:Elastic Tissue / Q000473:pathology*; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000473:pathology*; D016040:Lung Transplantation; D008297:Male; D010995:Pleural Diseases / Q000473:pathology; D055031:Primary Graft Dysfunction / Q000473:pathology*; D011658:Pulmonary Fibrosis / Q000473:pathology*
keywords: lung transplantion; obliterative bronchiolitis; pleuroparenchymal fibroelastosis; restrictive allograft syndrome