title: Does CT scanning predict the likelihood of a positive transbronchial biopsy in sarcoidosis?
abstract: BACKGROUND
  Transbronchial lung biopsy (TBB) has a variable diagnostic yield in sarcoidosis. It was hypothesised that the extent and pattern of parenchymal disease on CT scanning would predict the likelihood of a positive TBB result.
  
  
  METHODS
  Patients with sarcoidosis (n = 77) were included if they had undergone a CT scan within 6 weeks of TBB. Ethnicity, symptoms, pulmonary function and site and results of TBB and bronchoalveolar lavage (BAL) were recorded. CT scans were scored quantitatively for patterns of parenchymal disease (nodular, reticular, consolidation and ground glass) on a lobar basis.
  
  
  RESULTS
  39 patients (50.6%) had a positive TBB. Symptoms, ethnicity, treatment, lung volumes and chest radiographic stage were not predictors of a positive biopsy. Female gender, reduced percentage predicted carbon monoxide transfer factor and a higher percentage of lymphocytes in the BAL fluid were associated with a positive biopsy, as were higher total lung score, reticular pattern and ground-glass opacity. The associations were more significant for the total lobar score and the lobar ground-glass score of the lobe biopsied. On multivariate analysis gender, percentage of lymphocytes in the BAL fluid and total lung score were independent predictors of a positive TBB.
  
  
  CONCLUSIONS
  The total extent of parenchymal disease on the CT scan in addition to the pattern and lobar distribution predicts the likelihood of a positive TBB at bronchoscopy.
authors.affiliation: Auckland City Hospital, Auckland District Health Board, New Zealand. sdeboer@adhb.govt.nz
authors.forename: S
authors.initials: S
authors.lastname: de Boer
authors.forename: D G
authors.initials: DG
authors.lastname: Milne
authors.forename: I
authors.initials: I
authors.lastname: Zeng
authors.forename: M L
authors.initials: ML
authors.lastname: Wilsher
mesh_terms: D000328:Adult; D001706:Biopsy / Q000379:methods; D001980:Bronchi / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D017565:Sarcoidosis, Pulmonary / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed