Pleuroparenchymal fibroelastosis: the prevalence of secondary forms in hematopoietic stem cell and lung transplantation recipients

Abstract

Purpose: Pleuroparenchymal fibroelastosis (PPFE) is a rare form of interstitial pneumonia, characterized by elastotic fibrosis involving the pleura and subpleural parenchyma, predominantly in the upper lobes. PPFE can be either idiopathic or secondary and mostly occurs as a late complication of lung or hematopoietic stem cell transplantation (HSCT). The aim of this study was to evaluate the prevalence of secondary forms in transplant recipients.

Methods: An expert thoracic radiologist retrospectively reviewed high-resolution computed tomography exams of 700 HSCT recipients and 53 lung transplant recipients from the database of the Radiology Department of S. Orsola-Malpighi Hospital dating back from 2007. For each case that radiologically fulfilled PPFE criteria, the following details were retrieved: clinical characteristics, laboratory and functional data, pathologic findings (obtained from one patient) and metabolic data (obtained from three patients).

Results: Six cases clinically and radiologically consistent with PPFE were identified: two HSCT recipients (0.28%) and four lung transplant recipients (7.54%).

Conclusion: In this study, PPFE was strongly associated with lung transplants as a late complication, with a prevalence of 7.54%.

Figure 1

a, b. Case 5: PPFE secondary to an allogeneic bone marrow transplant with asymmetric distribution on the right and left lungs. Axial (a) and coronal (b) CT images show cystic bronchiectasis, pleuroparenchymal and blotchy opacities involving the entire lung including the lower zone, together with the superior hilar retraction and the volume reduction of the entire right lung (grade 4). In the left lung, axial (a) and coronal (b) CT images show cylindrical bronchiectasis, pleuroparenchymal opacities distributed in the upper zones, without consistent volume reduction (grade 1).

Figure 2

a, b. Case 3: PPFE (grade 2) secondary to a double-lung transplantation. Axial CT image (a) shows subpleural ground glass opacity (arrow) in the anterior segment of the right upper lobe; it rapidly progressed into a consolidation, as shown in the axial CT scan (b, arrow) taken after nine months. Also note new reticular abnormalities and ground glass opacity in the posterior segment.

Figure 3

a, b. Case 6: PPFE (grade 2–3) secondary to an autologous HSCT with progressive flattening of the chest. Axial CT scan at the level of the 6^th thoracic vertebra on admission (a) and after nine years (b): the ratio of the anteroposterior diameter of the thoracic cage (APDT) to the transverse diameter of the thoracic cage (TDT) decreased from 0.69 (a) to 0.63 (b) (13).

Figure 4

Case 3: PPFE (grade 2) secondary to a double-lung transplant. Coronal ¹⁸F-FDG PET/CT scan shows hypermetabolic areas corresponding to pleuroparenchymal upper lobes opacities (maximum standardized uptake value of 6.1, in the context of the upper left lobe atelectasis).