title: Focal dependent pleural thickening at MDCT: pleural lesion or functional abnormality?
abstract: OBJECTIVE
  To describe the characteristics of reversible focal pleural thickenings (PTs) mimicking real plaques, that firstly suggest asbestos exposure or pleural metastasis; to propose an imaging strategy and propose an explanation for their mechanism of formation.
  
  
  METHODS
  Retrospective review of data from 19 patients with PTs fitting the description of pleural plaques at chest computed tomography (CT) and presenting modifications (clearance or appearance) of at least one PT at an additional chest examination in prone position.
  
  
  RESULTS
  A total of 152 PTs were recorded on the first chest CT examinations with a range of two to 19 pleural opacities per patient. All PTs had a posterior distribution in the lower lobes. On the additional acquisitions, 144 PTs disappeared. Seventeen patients presented complete regression of PTs and two patients presented persistence of eight PTs.
  
  
  CONCLUSIONS
  Additional low dose acquisition in prone position should be performed in all patients presenting with focal PT in a dependent and basal location. This may allow to exclude a pleural plaque in case of asbestos exposure but also a pleural metastasis in oncologic patients. These reversible dependent PTs could be related to physiological focal accumulation of lymphatic fluid in subpleural area.
authors.affiliation: Department of Radiology, hôpital Pitié-Salpêtrière, Assistance publique-Hôpitaux de Paris, 47/83, boulevard de l'Hôpital, 75651 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Claude-Desroches
authors.forename: G
authors.initials: G
authors.lastname: Bierry
authors.forename: D
authors.initials: D
authors.lastname: Touitou-Gottenberg
authors.forename: J-L
authors.initials: JL
authors.lastname: Golmard
authors.forename: P A
authors.initials: PA
authors.lastname: Grenier
authors.forename: C
authors.initials: C
authors.lastname: Beigelman-Aubry
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010995:Pleural Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed