Pathological Comparisons of Paraseptal and Centrilobular Emphysema in Chronic Obstructive Pulmonary Disease.

Abstract

<b>Rationale:</b> Although centrilobular emphysema (CLE) and paraseptal emphysema (PSE) are commonly identified on multidetector computed tomography (MDCT), little is known about the pathology associated with PSE compared with that of CLE.<b>Objectives:</b> To assess the pathological differences between PSE and CLE in chronic obstructive pulmonary disease (COPD).<b>Methods:</b> Air-inflated frozen lung specimens (<i>n</i> = 6) obtained from patients with severe COPD treated by lung transplantation were scanned with MDCT. Frozen tissue cores were taken from central (<i>n</i> = 8) and peripheral (<i>n</i> = 8) regions of each lung, scanned with micro-computed tomography (microCT), and processed for histology. The core locations were registered to the MDCT, and a percentage of PSE or CLE was assigned by radiologists to each of the regions. MicroCT scans were used to measure number and structural change of terminal bronchioles. Furthermore, microCT-based volume fractions of CLE and PSE allowed classifying cores into mild emphysema, CLE-dominant, and PSE-dominant.<b>Measurements and Main Results:</b> The percentages of PSE measured on MDCT and microCT were positively associated (<i>P</i> = 0.015). The number of terminal bronchioles per milliliter of lung and cross-sectional lumen area were significantly lower and wall area percentage was significantly higher in CLE-dominant regions compared with mild emphysema and PSE-dominant regions (all <i>P</i> < 0.05), whereas no difference was found between PSE-dominant and mild emphysema samples (all <i>P</i> > 0.5). Immunohistochemistry showed significantly higher infiltration of neutrophils (<i>P</i> = 0.002), but not of macrophages, CD4, CD8, or B cells, in PSE compared with CLE regions.<b>Conclusions:</b> The terminal bronchioles are relatively preserved, whereas neutrophilic inflammation is increased in PSE-dominant regions compared with CLE-dominant regions in patients with COPD.