Disease progression in usual interstitial pneumonia compared with desquamative interstitial pneumonia: Assessment with serial CT

To determine the outcome of areas of ground-glass attenuation and assess disease progression on serial high-resolution CT (HRCT) scans of patients with biopsy specimen-proved usual interstitial pneumonia (UIP) and desquamative interstitial pneumonia (DIP). Materials and methods: Twelve patients with biopsy specimen-proved UIP and 11 patients with biopsy specimen-proved DIP who had initial and follow-up HBCT scans (median interval, 10 months) were reviewed. Eleven patients with UIP and 11 with DIP received treatment between the initial and follow-up CT scans. The scans were evaluated for the presence and extent of ground-glass attenuation, irregular linear opacities and honeycombing, and overall extent of parenchymal involvement. Results: On initial CT scans, all 12 patients with UIP had areas of ground-glass attenuation (mean ± SD extent, 30 ± 16%) and irregular lines (mean ± SD extent, 17 ± 7%) and 10 patients had honeycombing (mean ± SD extent, 10 ± 6%). All 11 patients with DIP had areas of ground-glass attenuation on initial HRCT scans (mean ± SD extent, 51 ± 26%), 5 patients had irregular linear opacities (mean ± SD extent, 5 ± 5%), and 1 patient had honeycombing. Nine of the 12 patients with UIP showed increase in the extent of ground-glass attenuation (n=6) or progression to irregular lines (n=2) or honeycombing (n=4) on follow-up as compared with only 2 patients with DIP who showed progression to irregular lines (n=1) or honeycombing (n=1) (p<0.01, χ² test). Conclusion: In patients with UIP, areas of ground- glass attenuation usually increase in extent or progress to fibrosis despite treatment. Areas of ground-glass attenuation in most patients with DIP remain stable or improve with treatment.