PMC6675970_01
A) Representative maximal expiratory flow versus absolute lung volume (MEFV) curves before and at various time intervals after allogeneic haematopoietic stem-cell transplantation (HSCT). It is noteworthy the rightward shift of MEFV curves following HSCT. B) Trajectory of lung function after HSCT. The shaded area represents normality range with upper and lower bounds corresponding to the higher (1.645 z-score) and lower (-1.645 z-score) limits of normal, i.e., the 5th and 95th percentiles, respectively, of the relevant reference values. IPS: idiopathic pneumonia syndrome; BOS: bronchiolitis obliterans syndrome; PPFE: pleuroparenchymal fibroelastosis; RV: residual volume; FEV1/FVC: forced expiratory volume in 1 s-to-forced vital capacity ratio; TLC: total lung capacity; DLCO: single-breath lung diffusing capacity for carbon monoxide.
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A) Computed tomography (CT) scan at tracheal carina showing features of pleuroparenchymal fibroelastosis. B) Automatic quantitative 3D analysis of the entire lungs. It is noteworthy, the significant extent of high attenuation areas (HAA-200 to -700 HU) consistent with fibrosis (16% of CT volume) and the lack of low attenuation areas (LAA<-950 HU) consistent with emphysema. C) Low-power (20 x), haematoxylin and eosin staining, micrograph showing visceral pleural fibrosis and elastosis, with sharp demarcation from normal lung parenchyma (black arrow). Neither granulomas nor inflammation appears in areas of fibrosis. D) High-power (100 x), elastic Van Gieson staining, micrograph showing an artery (black arrow) with a double layer of elastic fibers in the wall, thickening of media, and sub-occlusion of the lumen.
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CT scans showed "wedge-shaped" pleural thickening of upper and middle lung zones bilaterally, with reticular fibrotic pattern involving 16% of lung volume, without inspiratory low-attenuation areas suggestive of emphysema (Fig. 2A and B). Histology showed fibro-elastosis of sub-pleural lung parenchyma and visceral pleura, with no inflammation, or granulomas, or emphysematous areas (Fig. 2C and D).