Histopathologic variability in usual and nonspecific interstitial pneumonias

Findings of surgical lung biopsy (SLB) are important in categorizing patien ts with idiopathic interstitial pneumonia (IIP). We investigated whether hi stologic variability would be evident in SLB specimens from multiple lobes in patients with IIP. SLBs from 168 patients, 109 of whom had. multiple lob es biopsied, were reviewed by three pathologists. A diagnosis was assigned to each lobe. A different diagnosis was found between lobes in 26% of the p atients. Patients with usual interstitial pneumonia (UIP) in all lobes were categorized as concordant for UIP (n = 51) and those with UIP in at least one lobe were categorized as discordant for UIP (n = 28). Patients with non specific interstitial pneumonia (NSIP) in all, lobes were categorized as ha ving fibrotic (n = 25) or cellular NSIP (n = 5). No consistent distribution of lobar histology was noted. Patients concordant for UIP were older (63 /- 9 [mean +/- SD] yr; p < 0.05 as compared with all other groups) than tho se discordant for UIP (57 +/- 12 yr) or with fibrotic NSIP (56 +/- 11 yr) o r cellular NSIP (50 +/- 9 yr). Semiquantitative high-resolution computed to mography demonstrated a varied profusion of fibrosis (p < 0.05 for all grou p comparisons), with more fibrosis in concordant UIP (2.13 <plus/minus> 0.6 2) than in discordant UIP (1.42 +/- 0.73), fibrotic NSIP (0.83 +/- 0.58), o r cellular NSIP (0.44 +/- 0.42). Survival was better for patients with NSIP than for those in both UIP groups (p < 0.001), although survival in the tw o UIP groups was comparable (p = 0.16). Lobar histologic variability is fre quent in patients with IIP, patients with a histologic pattern of UIP in an y lobe should be classified as having UIP.