Fibrosing pneumonia – how to diagnose, and how to recognize the etiology?

Abstract

Abstract Background Fibrosing pneumonias are a group of interstitial lung diseases with a different etiologic background and divergent prognosis. They are differentiated into usual interstitial pneumonia (UIP), non-specific interstitial pneumonia (NSIP), and organizing pneumonia (OP). Some of these entities were initially described by A. Liebow. Main In the 90ties the main differences in survival lead to the separation of UIP/IPF as a disease with dismal outcome, from the prognostically better NSIP and OP. Later it was shown that fibrosing NSIP confers an almost identical worse prognosis. Under the heading of pulmologists a classification was created, where the diagnosis has to be established by a multidisciplinary team, based on pattern recognition done by radiologists and pathologists. A clinical diagnosis has to be established based on the patterns: UIP pattern was the basis for IPF, NSIP pattern for the clinical diagnosis NSIP, and organizing pneumonia pattern for the diagnosis of cryptogenic organizing pneumonia. This created confusion, because the pattern UIP was taken almost as synonymous with idiopathic pulmonary fibrosis (IPF). Later on in many articles and classifications the role of the pathologic diagnosis was diminished, because pulmologists based their diagnosis on CT-scan and clinical presentation. This resulted in less tissue biopsies but also delay and misinterpretation of diseases. Even new techniques in tissue biopsies such as cryobiopsy was regarded as unnecessary. Conclusion Tissue analysis in fibrosing pneumonias is still the gold standard in making a diagnosis and also evaluating the etiologic background. After an analysis the findings should be discussed in a multidisciplinary board to establish a final diagnosis and a treatment option for the patient.