High-resolution computed tomography findings in chronic eosinophilic vs. cryptogenic organising pneumonia

BACKGROUND : The similar clinical and computed tomography (CT) characteristics of cryptogenic organising pneumonia (COP) and chronic eosinophilic pneumonia (CEP) make precise diagnosis challenging. OBJECTIVES : To help differentiate between COP and CEP using high-resolution CT (HRCT). DESIGN: Clinical data and HRCT images of COP and CEP patients referred to Masih Daneshvari Hospital, Tehran, Iran, from 2007 to 2015 were reviewed. Diagnosis of COP or CEP was confirmed using open lung biopsy or a combination of transbronchial biopsy, bronchoalveolar lavage fluid (BALF) analysis, peripheral eosinophilia and a favourable response to corticosteroids. RESULTS : Ground-glass opacity, a dominant ground-glass pattern, upper-lobe pneumonia, increased thickness of bronchial walls and a mosaic pattern in the lungs were more frequent in CEP. Lower-lobe pneumonia, subpleural reticulation, a dominant consolidation pattern, nodules and masses, non-septal linear opacities, bronchial dilation and a reverse halo sign were more frequent in COP. History of asthma, wheezing and peripheral eosinophilia was significantly more common in CEP than in COP. CONCLUSION: Distinguishing between CEP and COP based on HRCT alone is not always possible. However, in many cases, especially if the correct diagnosis cannot be established by other means, certain HRCT features can be very helpful.