Pleuroparenchymal fibroelastosis: a pattern of chronic lung injury.

Pleuroparenchymal fibroelastosis (PPFE) is a rare condition currently described as an upper lobe subpleural and interstitial proliferation of predominantly elastic fibers. The etiology is unknown, and no specific diagnostic criteria have been reported. Here we report 5 cases of PPFE, 1 man and 4 women, 3 of them diagnosed at the time autopsy, 1 diagnosed in an explanted lung, and 1 diagnosed on a surgical wedge biopsy. The average age of diagnosis among this series is 73 years, and the duration of pulmonary symptoms ranged from 14 months to at least 9 years. Two patients had been exposed to specific medications (daptomycin and dapsone) preceding the development of pulmonary symptoms, and 1 patient developed eosinophilic pneumonia in the course of the disease. Four patients had clinical evidence of fibrous interstitial pneumonia. We found evidence of diffuse parenchymal fibroelastosis involving both upper and lower lobes in all 5 cases, suggesting that the disease may be a more diffuse condition than previously reported. PPFE may actually represent a pattern of chronic lung injury rather than a specific entity and may be seen in association with a variety of clinicoradiologic conditions. Based on our findings in this series and the most recent publications of the subject, we propose the following set of diagnostic criteria for PPFE: multilobar subpleural and/or centrilobular fibrous interstitial pneumonia characterized by an extensive (>80%) proliferation of elastic fibers in nonatelectatic lung, along with absent to mild chronic inflammation, and absent to rare granulomas.