• Organising pneumonia
• histopathology/cytology
• atoll sign
• reverse-halo sign

A man presented as an urgent referral to the interstitial lung disease outpatient clinic with a 5 week history of fever, night sweats, shortness of breath and malaise. His admission chest x-ray showed patchy consolidation within both lungs, and a subsequent CT demonstrated multiple parenchymal ring opacities (figure 1 and figure 2A). On the basis of the unusual CT appearances he subsequently proceeded to an open lung biopsy which demonstrated polypoid buds of intra-alveolar granulation tissue or Masson bodies, consistent with a histopathological diagnosis of organising pneumonia (figure 3). He was treated with intravenous …