Diagnostic evaluation of diffuse parenchymal lung disease

The diagnostic process in DPLDs begins with a clinical evaluation that includes a history, physical examination, chest radiograph, and lung function tests. On the basis of this information, the patients may be divided into two groups: cases that do not represent IIP, owing to recognition of associated conditions or underlying exposures, and cases that could represent IIP. Patients in the latter category typically undergo a HRCT scan. This generally results in four categories of patients: (1) those with distinctive features that allow for a confident diagnosis of IPF/usual interstitial pneumonia in the appropriate clinical setting, (2) those with atypical clinical or HRCT features for IPF, (3) those with features diagnostic of another DPLD such as PLCH, and (4) those with suspected other forms of DPLD. Although many patients will go directly to surgical lung biopsy, some patients may undergo TBBx or BAL If these findings are nondiagnostic, a surgical lung biopsy may be necessary to separate the various IIPs from non-IIP.