Pleuroparenchymal Fibroelastosis: Its Pathological Characteristics

Pleuroparenchymal fibroelastosis (PPFE) is a distinct pattern of pulmonary fibrosis which often runs a rapidly progressive course with a poor prognosis, and it is likely to be introduced as a separate entity in the new classification scheme of idiopathic interstitial pneumonias. It is characterised by pleural fibrosis and subpleural fibroelastosis, with an upper lobe predominance. In addition to cases following lung and bone marrow transplantation, familial and idiopathic cases have been described. The literature on PPFE is fragmented, however, and primarily consists of small case series, lacking a uniform methodology of clinical, radiological and histopathological description. In this review article, most previously published reports of PPFE in the English-language literature will be discussed and the salient clinical and histopathological data analysed to arrive at a working definition of PPFE in daily histopathological practice, and to aid the generation of a unifying hypothesis regarding its potential aetiologies and pathogenesis.