title: Comparative study of high-resolution CT findings between autoimmune and secondary pulmonary alveolar proteinosis.
abstract: BACKGROUND
  Acquired pulmonary alveolar proteinosis (PAP) has been reclassified into autoimmune or secondary PAP according to the occurrence of serum granulocyte macrophage colony-stimulating factor autoantibody. Most patients undergo high-resolution CT (HRCT) scanning in order for physicians to make a differential diagnosis of diffuse lung diseases, but no information is available to distinguish the HRCT scan features of secondary PAP from those of autoimmune PAP. The objective of this study was to characterize the HRCT scan features of autoimmune and secondary PAP.
  
  
  METHODS
  HRCT scans of 42 patients (21 patients each in the autoimmune PAP and secondary PAP groups) were centrally collected and evaluated in a blinded manner.
  
  
  RESULTS
  Ground-glass opacities (GGO) were a major finding in both the autoimmune PAP and secondary PAP groups. In the secondary PAP group, GGOs typically showed a diffuse pattern (62%), whereas GGOs showed a patchy geographic pattern in the autoimmune PAP group (71%; p < 0.005). The so-called "crazy-paving" appearance and subpleural sparing were frequently seen in the autoimmune PAP group (both 71%), whereas they were less frequently seen in the secondary PAP group (14% and 33%, respectively). The involved area of GGO was even in craniocaudal distribution for the secondary PAP group, whereas it was predominant in the lower lung field compared with the upper lung field in the autoimmune PAP group (p < 0.05).
  
  
  CONCLUSIONS
  Typical HRCT scan findings for autoimmune PAP patients were GGO with a patchy geographic pattern, subpleural sparing, crazy-paving appearance, and predominance in the lower lung field. These findings were rather infrequent for secondary PAP patients.
authors.affiliation: Department of Respiratory Medicine, Kyorin University Hospital, Tokyo, Japan.
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Ishii
authors.affiliation: Divisions of Pulmonary Biology and Medicine, Children's Hospital Research Foundation, Cincinnati, OH.
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Trapnell
authors.affiliation: Bioscience Medical Research Center, Niigata University Medical and Dental Hospital, Niigata, Japan.
authors.forename: Ryushi
authors.initials: R
authors.lastname: Tazawa
authors.affiliation: Department of Diffuse Lung Diseases and Respiratory Failure, Clinical Research Center, NHO Kinki-Chuo Chest Medical Center, Osaka, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Department of Radiology, National Kinki Chuo Hospital for Chest Disease, Osaka, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Akira
authors.affiliation: Department of Internal Medicine, NHO Nagoya Medical Center, Aichi, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Kogure
authors.affiliation: Department of Internal Medicine, Kobe City Medical Center General Hospital, Hyogo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tomii
authors.affiliation: Department of Respiratory Medicine, Niigata University Medical and Dental Hospital, Niigata, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Takada
authors.affiliation: Department of Respiratory Medicine, International Medical Center of Japan, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hojo
authors.affiliation: Department of Respiratory Medicine, Dokkyo University Hospital, Saitama, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Ichiwata
authors.affiliation: Department of Respiratory Medicine, Kyorin University Hospital, Tokyo, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Goto
authors.affiliation: Bioscience Medical Research Center, Niigata University Medical and Dental Hospital, Niigata, Japan. Electronic address: radical@med.niigata-u.ac.jp.
authors.forename: Koh
authors.initials: K
authors.lastname: Nakata
mesh_terms: D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000000981:diagnostic imaging; D002272:Carcinoembryonic Antigen / Q000097:blood; D003371:Cough; D005260:Female; D005334:Fever; D006801:Humans; D008297:Male; D008875:Middle Aged; D011649:Pulmonary Alveolar Proteinosis / Q000000981:diagnostic imaging* / Q000209:etiology / Q000276:immunology* / Q000503:physiopathology; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D002272:Carcinoembryonic Antigen; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D