Reverse bat wing pulmonary opacities refer to peripheral opacities of the lungs, sparing the perihilar region. It is a relatively unusual appearance with a fairly narrow differential 1:
- chronic eosinophilic pneumonia
- organizing pneumonia (formerly bronchiolitis obliterans with organizing pneumonia (BOOP))
- entities previously classified as bronchoalveolar carcinoma - now entities in the spectrum of adenocarcinoma in situ, minimally invasive adenocarcinoma and invasive adenocarcinoma of the lung
- pulmonary contusion: in the setting of trauma
- pulmonary hemorrhage +/- infarction: in the context of pulmonary embolism
- pulmonary vasculitides
- aspiration (pulmonary aspiration)
