title: Nine pulmonary aspiration syndrome cases of atypical clinical presentation, in which the final diagnosis was obtained by histological examinations.
abstract: BACKGROUND
  While pulmonary aspiration syndrome (PAS) is primarily clinically diagnosed, atypical PAS cases can be misdiagnosed clinically and are more accurately diagnosed histologically. To elucidate clinicopathological features of these rare cases, we examined PAS cases determined by histological examination of transbronchial lung biopsy (TBLB) specimens.
  
  
  METHODS
  Of 6105 TBLB cases investigated from 1990 to 2007, 11 were diagnosed as PAS based on histology. Of these, we examined 9 records in detail, as the medical records for 2 cases were unavailable.
  
  
  RESULTS
  Histopathological findings indicated 8 patients with aspiration pneumonia and 1 with diffuse aspiration bronchiolitis. However, the pre-bronchoscopy diagnoses included lung cancer, mycobacteriosis, organizing pneumonia, repetitive pneumonia, fungal infection, and interstitial pneumonia. PAS was not considered before TBLB. Only 4 of the 9 patients developed subjective symptoms including fever and cough with sputum production. Laboratory findings demonstrated elevation of white blood cell (WBC) count in only 1 patient and elevation of C reactive protein (CRP) level in 4 patients. Radiographic examination revealed abnormal findings in the dorsal right lower lobes, which was the most vulnerable site for aspiration pneumonia, and also in the upper and ventral portions of the lung. Although the characteristic findings of PAS were scarce, all patients had conditions predisposing to aspiration; i.e., gastrectomy, excessive alcohol drinking, post-cerebral infarction, and sinobronchial syndrome.
  
  
  CONCLUSIONS
  We diagnosed 9 PAS patients on the basis of histological findings that were distinct from clinical findings. Despite presenting with variable symptoms and laboratory and radiographic findings, they all exhibited predisposing factors to aspiration.
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: mshimada-in@tokyo-hosp.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shimada
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan; Department of Pulmonary Medicine, Hitachinaka Education and Research Center, University of Tsukuba, Japan. Electronic address: shinjit-tky@umin.ac.jp.
authors.forename: Shinji
authors.initials: S
authors.lastname: Teramoto
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: hmatui-in@tokyo-hosp.jp.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Matsui
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: tamura-in@tokyo-hosp.jp.
authors.forename: Atsuhisa
authors.initials: A
authors.lastname: Tamura
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: bob-in@tokyo-hosp.jp.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Akagawa
authors.affiliation: Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: kenohta@tokyo-hosp.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Ohta
authors.affiliation: Clinical Research Center, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: hebisawa-in@tokyo-hosp.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Hebisawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000379:methods; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011015:Pneumonia, Aspiration / Q000175:diagnosis* / Q000473:pathology*; D013902:Radiography, Thoracic; D013577:Syndrome; D014057:Tomography, X-Ray Computed
keywords: Aspiration pneumonia; C reactive protein; CRP; Fungi-flora-Y; Histological examination; MAC; PAS; Pulmonary aspiration syndrome; TBLB; Transbronchial lung biopsy; WBC; mycobacterium-avium-complex; pulmonary aspiration syndrome; transbronchial lung biopsy; white blood cell