Update in Diffuse Parenchymal Lung Diseases 2005

Abstract

CLINICAL ADVANCES A number of publications have shed light on important clinical concepts surrounding the clinical evaluation and management of diffuse parenchymal lung diseases (DPLDs). These include approaches to idiopathic interstitial pneumonias (IIPs), including nonspecific interstitial pneumonia (NSIP) and idiopathic pulmonary fibrosis (IPF; idiopathic usual interstitial pneumonia [UIP]), connective tissue–associated DPLD, hypersensitivity pneumonitis (HP), and lymphangioleiomyomatosis (LAM). IIPs A series of sentinel observations have addressed diagnostic issues, staging approaches, unique phenotypes, and management strategies for IIPs. Diagnostic approach. The approach to diagnosis in patients with DPLDs has continued to evolve over the past decade. A recent centennial review described the major impact of highresolution computed tomography (HRCT) in guiding the diagnostic approach to patients with suspected IIP (1). It is evident that stereotypical imaging features have been described for many DPLDs, including some of the IIPs (2). The diagnostic accuracy of the radiological features of UIP has been demonstrated in well-designed clinical studies (3–5). Despite these data, there remains diagnostic confusion regarding the separation of UIP from other IIPs, particularly NSIP (6). On the other hand, increasing data have suggested that predominance of ground-glass opacity with no honeycombing is more common in NSIP. In a recent series, such a pattern was seen in 96% of patients with NSIP and 59% of patients with UIP (7). Unfortunately, the overall diagnostic accuracy of HRCT for separating these two disorders was 70% in this series. The contrast between expert and less experienced radiologists in applying HRCT criteria to the diagnosis of IPF has recently been reported in data from a landmark clinical therapeutic trial (8). As part of this trial, HRCT scans were interpreted by clinical site radiologists and an expert radiology core using predefined criteria. The core radiologists agreed with a diagnosis of IPF in 99% of those diagnosed by site radiologists; little difference was found if the clinical site was an “academic” center or a community-based practice. A survey of American College of Chest Physician members (52.6% responses to the survey) suggested that 67% of respondents accepted HRCT diagnosis for IPF (9). Interestingly, one investigative group has demonstrated that interaction between expert clinicians and radiologists improves the interobserver agreement of the former in evaluating patients with IIPs (10). It is evident that a consensus is developing that typical features of UIP in the appropriate clinical setting can be used to accurately diagnose IPF. In other IIPs, particularly