title: Relationship between fibroblastic foci profusion and high resolution CT morphology in fibrotic lung disease.
abstract: BACKGROUND
  Fibroblastic foci profusion on histopathology and severity of traction bronchiectasis on highresolution computed tomography (HRCT) have been shown to be predictors of mortality in patients with idiopathic pulmonary fibrosis (IPF). The aim of this study was to investigate the relationship between fibroblastic foci (FF) profusion and HRCT patterns in patients with a histopathologic diagnosis of usual interstitial pneumonia (UIP), fibrotic non-specific interstitial pneumonia (NSIP) and chronic hypersensitivity pneumonitis (CHP).
  
  
  METHODS
  The HRCT scans of 162 patients with a histopathologic diagnosis of UIP or fibrotic NSIP (n = 162) were scored on extent of groundglass opacification, reticulation, honeycombing, emphysema and severity of traction bronchiectasis. For each patient, a fibroblastic foci profusion score based on histopathologic appearances was assigned. Relationships between extent of fibroblastic foci and individual HRCT patterns were investigated using univariate correlation analysis and multivariate linear regression.
  
  
  RESULTS
  Increasing extent of reticulation (P < 0.0001) and increasing severity of traction bronchiectasis (P < 0.0001) were independently associated with increasing FF score within the entire cohort. Within individual multidisciplinary team diagnosis subgroups, the only significant independent association with FF score was severity of traction bronchiectasis in patients with idiopathic pulmonary fibrosis (IPF)/UIP (n = 66, r(2) = 0.19, P < 0.0001) and patients with chronic hypersensitivity pneumonitis (CHP) (n = 49, r(2) = 0.45, P < 0.0001). Furthermore, FF score had the strongest association with severity of traction bronchiectasis in patients with IPF (r(2) = 0.34, P < 0.0001) and CHP (r(2) = 0.35, P < 0.0001). There was no correlation between FF score and severity of traction bronchiectasis in patients with fibrotic NSIP. Global disease extent had the strongest association with severity of traction bronchiectasis in patients with fibrotic NSIP (r(2) = 0.58, P < 0.0001).
  
  
  CONCLUSIONS
  In patients with fibrotic lung disease, profusion of fibroblastic foci is strikingly related to the severity of traction bronchiectasis, particularly in IPF and CHP. This may explain the growing evidence that traction bronchiectasis is a predictor of mortality in several fibrotic lung diseases.
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. slfwalsh@gmail.com.|Department of Radiology, Kings College Hospital Foundation Trust, Denmark Hill, London, SE5 9RS, UK. slfwalsh@gmail.com.
authors.forename: Simon L F
authors.initials: SL
authors.lastname: Walsh
authors.affiliation: Interstitial Lung Diseases Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: Athol U
authors.initials: AU
authors.lastname: Wells
authors.affiliation: Department of Clinical Sciences, Section of Radiology, University of Parma, Via Gramsci 14, 43126, Parma, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Sverzellati
authors.affiliation: Department of Radiology, St Georges Hospital, Tooting, London, SW17 0QT, UK.
authors.forename: Anand
authors.initials: A
authors.lastname: Devaraj
authors.affiliation: Medisch Centrum Haaglanden, The Hague Area, Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: von der Thüsen
authors.affiliation: Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Yousem
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Scottsdale, Arizona, USA.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Colby
authors.affiliation: Department of Histopathology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Nicholson
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Hansell
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed / Q000379:methods*