title: Pleural disease in silicosis: pleural thickening, effusion, and invagination.
abstract: OBJECTIVE
  To retrospectively evaluate pleural disease on images from patients with autopsy-proved silicosis.
  
  
  METHODS
  The study had institutional review board approval, and informed consent from relatives of diseased subjects was waived. Lung specimens were obtained at autopsy in 110 men (mean age, 72 years) who had been followed up radiologically for a mean of 14.8 years. Computed tomographic (CT) scans obtained within 2 years before death were examined for presence of pleural thickening; shape, composition, size, and subpleural location of progressive massive fibrosis (PMF); and pleural invagination (bandlike structure between lesion and pleura). Lung specimens were reviewed and compared with CT findings. Serial chest radiographs and CT scans were reviewed for presence of pleural effusion. Association between radiographic findings and pleural invagination was analyzed with chi2 and Student t tests. Multiple logistic regression analysis was used to find predictive variables for pleural invagination.
  
  
  RESULTS
  Pleural effusion was found in 12 (11%) patients at chest radiography and CT, and thickening was found in 64 (58%) patients at CT; the latter finding was significantly more frequent with complicated silicosis (P < .001). At CT, 128 PMF lesions were seen, 39 (30%) of which showed pleural invagination; CT scans showed pleural thickening in 36 (92%) of these 39 lesions. In 17 (44%) PMF lesions, CT scans depicted a bandlike structure that was pathologically confirmed to represent invaginated pleura in all cases. Pathologic presence of invagination was significantly associated with pleural thickening (P < .001), ipsilateral pleural effusion (P < .01), interstitial fibrosis (P < .05), and the nearness of PMF to the pleura (P < .005). Multiple logistic regression analysis showed that pleural thickening (odds ratio, 62.51; 95% confidence interval [CI]: 5.564, 70.2) and pleural effusion (odds ratio, 25.865; 95% CI: 1.992, 335.8) were significant CT variables associated with presence of pathologic pleural invagination (P = .001 and .013, respectively). Five PMF lesions had radiographic features of rounded atelectasis.
  
  
  CONCLUSIONS
  Various pleural abnormalities can occur in silicosis, especially in advanced disease.
authors.affiliation: Department of Radiology and Pathology, Dokkyo University School of Medicine, Mibu, Tochigi 321-0293, Japan. arakawa@dokkyomed.ac.jp
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Arakawa
authors.forename: Koichi
authors.initials: K
authors.lastname: Honma
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Saito
authors.forename: Hisao
authors.initials: H
authors.lastname: Shida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Morikubo
authors.forename: Narufumi
authors.initials: N
authors.lastname: Suganuma
authors.forename: Mutsuhisa
authors.initials: M
authors.lastname: Fujioka
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D010995:Pleural Diseases / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology*; D010996:Pleural Effusion / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D012189:Retrospective Studies; D012829:Silicosis / Q000150:complications*; D014057:Tomography, X-Ray Computed