Distribution of emphysema and fibrosis in idiopathic pulmonary fibrosis with coexisting emphysema

Aims Combined pulmonary fibrosis and emphysema (CPFE) is a syndrome that results from tobacco smoking. Emphysema and fibrosis in CPFE patients have been considered to exist separately, with emphysema in the upper lobes and interstitial pneumonia in the lower lobes. The aim of this study was to examine the intrapulmonary distribution of fibrosis and emphysema in clinically diagnosed patients with idiopathic pulmonary fibrosis (IPF) and coexisting emphysema. Methods and results Among IPF patients (n = 40) who had been autopsied or pneumonectomised for lung transplantation from 1993 to 2018, we retrospectively selected patients with IPF and coexisting emphysema (n = 19) on the basis of the appearance on chest computed tomography (IPF patients with emphysema). We then histologically determined the intrapulmonary distribution of emphysema and fibrosis in the upper lobes and the lower lobes separately. In 15 of the 19 IPF patients with emphysema (79%), fibrosis and emphysema coexisted in the upper lobes and the lower lobes. No patients showed emphysema exclusively in the upper lobes and fibrosis exclusively in the lower lobes. Conclusions In the autopsied and pneumonectomised specimens of IPF patients with emphysema, craniocaudal separation of emphysema and fibrosis (emphysema in the upper lobes and interstitial pneumonia in the lower lobes) was histologically rare; coexistence or collision of fibrosis and emphysema in each lobe was common.