Noninfectious mimics of community-acquired pneumonia.
A broad spectrum of diseases and clinical syndromes can masquerade as community-acquired pneumonia (CAP). Many such disorders, such as hypersensitivity pneumonitis (HP), chronic eosinophilic pneumonia (CEP), bronchiolitis obliterans--organizing pneumonia (BOOP), reactions to drugs or exogenous agents, systemic vasculitis, and alveolar hemorrhage (AH; pulmonary-renal) syndromes, are immune-mediated and warrant treatment with corticosteroids or immunosuppressive agents. In addition, rare neoplastic and lymphoproliferative disorders, and conditions of uncertain etiology (eg, pulmonary alveolar proteinosis [PAP]) may have clinical and radiographic features that overlap with infectious causes of pneumonia. Distinguishing infectious from noninfectious causes of pneumonia may be difficult, and requires the use of ancillary serologic studies and often histologic material to establish a precise etiologic diagnosis. For some of these disorders (particularly Wegener's granulomatosis [WG], systemic necrotizing vasculitis [SNV], and antiglomerular basement antibody disease [anti-GBM disease]), serologic markers are invaluable in confirming the diagnosis and monitoring the course of the disease. In this report, we review the salient clinical and histologic features of these diverse diseases, and present a diagnostic and therapeutic approach.
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0360.
J P
JP
Lynch
R G
RG
Sitrin
D001424:Bacterial Infections / Q000175:diagnosis* / Q000209:etiology; D003937:Diagnosis, Differential; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis* / Q000209:etiology; D008175:Lung Neoplasms / Q000175:diagnosis / Q000209:etiology; D011014:Pneumonia / Q000175:diagnosis* / Q000209:etiology