title: Pulmonary alveolar proteinosis versus exogenous lipoid pneumonia showing crazy-paving pattern: Comparison of their clinical features and high-resolution CT findings.
abstract: BACKGROUND
  Although pulmonary alveolar proteinosis (PAP) and exogenous lipoid pneumonia (ELP) require different treatment strategies, both manifest as a crazy-paving pattern on CT and often have similar clinical manifestations and radiologic features.
  
  
  OBJECTIVE
  To investigate the clinical features and high-resolution computed tomography (HRCT) findings of PAP and ELP showing the crazy-paving pattern.
  
  
  METHODS
  The clinical features and HRCT findings of eight patients with pathologically proven PAP and six patients with pathologically proven ELP showing the crazy-paving pattern were retrospectively evaluated. Two radiologists analyzed the HRCT findings of PAP and ELP in consensus in terms of the presence, severity, and extent of illdefined centrilobular nodules, consolidations, ground-glass opacities (GGOs), reticulations, and the crazy-paving pattern.
  
  
  RESULTS
  With respect to the clinical features of these two diseases, all patients with ELP were retrospectively found to have a history of oil ingestion. In terms of the HRCT findings, ill-defined centrilobular nodules were seen in five of six patients (83%) with ELP, whereas they were not present in any patient with PAP (P=0.003). Consolidation was also more frequently present in patients with ELP (83%) than in those with PAP (11%), which was statistically different (P=0.0265). In terms of the severity and extent, the crazy-paving pattern and reticulations on HRCT were significantly more extensive and severe in patients with PAP than in those with ELP.
  
  
  CONCLUSIONS
  PAP and ELP with the crazy-paving pattern have several distinctive characteristics with respect to their HRCT findings as well as history of oil ingestion, and can therefore be distinguished from one another.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.
authors.forename: Hei Kyung
authors.initials: HK
authors.lastname: Choi
authors.forename: Chang Min
authors.initials: CM
authors.lastname: Park
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Goo
authors.forename: Hyun Ju
authors.initials: HJ
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011017:Pneumonia, Lipid / Q000000981:diagnostic imaging* / Q000473:pathology; D011649:Pulmonary Alveolar Proteinosis / Q000000981:diagnostic imaging* / Q000473:pathology; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*