title: [Noninfectious differential diagnoses of pneumonia].
abstract: BACKGROUND
  In patients with a clinical suspicion of pneumonia, typical clinical and laboratory features along with the detection of infiltrates on chest X‑ray are as a rule considered diagnostic and therapy is immediately initiated; however, studies have shown that in up to 5% of patients with an initial suspicion of pneumonia, another noninfectious pulmonary disease was the underlying cause. Early recognition and differentiation of diseases mimicking pneumonia are prerequisites for an adequate therapy.
  
  
  OBJECTIVE
  The aim of this review is to present the important noninfectious differential diagnoses of pneumonia and to provide the reader with tools for a systematic diagnostic approach.
  
  
  METHODS
  A literature search was carried out.
  
  
  RESULTS
  As alterations in the lungs often result in similar imaging appearances and a differentiation between transudates, exsudates, blood and cells is not feasible by chest X‑ray or CT, a systematic approach is essential to make an appropriate diagnosis. Hence, consideration of the temporal course, predominant pattern, distribution of findings, additional findings and clinical presentation are indispensable.
authors.affiliation: Universitätsklinik für Radiologie und Nuklearmedizin, Medizinische Universität Wien, Währingergürtel 18-20, 1090, Wien, Österreich. alice.wielandner@meduniwien.ac.at.
authors.forename: A
authors.initials: A
authors.lastname: Wielandner
authors.affiliation: Universitätsklinik für Radiologie, Medizinische Universität Freiburg, Hugstetterstraße 55, 79106, Freiburg, Deutschland.
authors.forename: P
authors.initials: P
authors.lastname: Agarwal
authors.affiliation: Universitätsklinik für Radiologie und Nuklearmedizin, Medizinische Universität Wien, Währingergürtel 18-20, 1090, Wien, Österreich.
authors.forename: A
authors.initials: A
authors.lastname: Toelly
authors.affiliation: Abteilung für Radiologie, Krankenhaus Hietzing, Wolkersbergenstraße 1, 1130, Wien, Österreich.
authors.forename: C
authors.initials: C
authors.lastname: Bardach
mesh_terms: D003937:Diagnosis, Differential; D003951:Diagnostic Errors / Q000517:prevention & control*; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D011014:Pneumonia / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Chest X ray; Computed tomography; Predominant pattern; Temporal course; Treatment resistant