Idiopathic Pleuroparenchymal Fibroelastosis By Joyce Lee, MD, MAS, University of Colorado School of Medicine Reviewed / Revised Jun 2021 | Modified Sep 2022 View Patient Education Etiology Symptoms and Signs Diagnosis Prognosis Treatment Topic Resources Idiopathic Pleuroparenchymal... Idiopathic pleuroparenchymal fibroelastosis is a rare idiopathic interstitial pneumonia that predominantly involves the upper lobes of the lungs and is slowly progressive.