Radiopaedia.org

There is a predominant peribronchial and subpleural distribution of focal opacities some of which demonstrate surrounding ground glass.  There is an apico-basal gradient with the mid and lower zones more significantly affected.  There is relative sparing of the central parahilar regions of the lungs. No evidence of 'Air Crescent' sign demonstrated. Nodular opacities at the apices. No pleural effusion identified. Mild pleural thickening. No evidence of bronchiectasis. No evidence of mosaic attenuation. No thoracic lymphadenopathy is identified. No sinister bone lesion identified. The imaged solid organs of the upper abdomen are unremarkable.

Conclusion: The radiological appearances are consistent with cryptogenic organising pneumonia and graft versus host disease as the most likely aetiologies.