Histological Changes Are Background Factors in Acute Exacerbation of Usual Interstitial Pneumonia Pattern/Lesions Following Lung Resection

Abstract

Objective. The objective was to determine the histological features related to acute exacerbation of usual interstitial pneumonia pattern (UIP lesion). Materials and methods. The subjects were 12 patients with a diffuse (dense fibrosis extending more than 1 cm from the pleura) or a focal (less than 1 cm) UIP lesion showing acute exacerbation following lobectomy or more for lung cancer (exacerbation group), and 24 comparable patients without acute exacerbation (stable group). The exacerbation group: all men, mean±SD 68±7 years, 7 diffuse and 5 focal UIP lesions. We quantitatively examined the activity and tissue damage related to the UIP lesion on 3 representative histological slides by hematoxylin and eosin staining and by immunohistochemical staining using anti-EMA antibody and anti-ubiquitin antibody. Results. Significant differences (<0.05) were demonstrated: a. the thickness of interstitial inflammation continuous with dense fibrosis; exacerbation group 2.4±1.3, stable group 1.3±1.3 mm, b. number of granulation tissue in and next to dense fibrosis; 21.4±12.2, 12.6±9.1, c. quantification of interstitial inflammatory change with granulation tissue apart from dense fibrosis; 7±5.9, 3.7±3, d. quantification of acute interstitial inflammatory change with fibrin exudation; 1.6±3.2, 0.25±0.6, respectively. Conclusion. The above findings suggestive of UIP activities might be background factors in acute exacerbation.