[Pleuroparenchymal fibroelastosis is a new entity which can be mistaken for sarcoidosis]. 
Pleuroparenchymal fibroelastosis is an idiopathic interstitial pneumonia, recently recognized as a new entity by American Thoracic Society/European Respiratory Society.  We present the first Danish cases of pleuroparenchymal fibroelastosis in two young sisters, who had complained of dyspnoea since childhood.  Their lung function was reduced at referral (forced expiratory volume in 1st sec.:  36-43%, forced vital capacity: 34-41%, diffusing capacity for carbon monoxide: 35%).  High resolution CT showed apical peripheral consolidation, pleural thickening, traction bronchiectasis and enlarged lymph nodes of both patients; compatible with pleuroparenchymal fibroelastosis.  Due to low lung function, lung biopsies were not performed.