Peripheral Distribution of Pulmonary Opacities

The reverse bat wing or reverse butterfly pattern of pulmonary opacities can be seen with:

• Acute respiratory distress syndrome:
• Lung contusion:
• Cryptogenic organizing pneumonia:
• Simple pulmonary eosinophilia: Loeffler syndrome. Migratory peripheral ground-glass opacity or airspace consolidation involving mainly the middle and upper lung zones. Single or multiple airspace nodules with surrounding ground-glass opacity can also be seen.
• Chronic eosinophilic pneumonia (shown above): Classic radiographic finding is nonsegmental peripheral airspace consolidation involving mainly the upper lobes.
• Pneumonia:
• Pulmonary infarction:
• Sarcoidosis: Pulmonary nodules and masses when seen in sarcoidosis (15%–25% of patients with parenchymal opacities) are ill-defined and irregular and represent coalescent interstitial granulomas. They may be located in perihilar or peripheral regions. Small satellite nodules can be seen around them ("galaxy sign", nonspecific).
• Vasculitides:

References

• Criado E, Sánchez M, Ramírez J, Arguis P, de Caralt TM, Perea RJ, Xaubet A. Pulmonary sarcoidosis: typical and atypical manifestations at high-resolution CT with pathologic correlation. Radiographics. 2010 Oct;30(6):1567-86. Review.
• Gamut F-13. in Gamuts in Radiology - Reeder and Felson - 4th ed (Springer, 2003).
• Gaensler EA, Carrington CB. Peripheral opacities in chronic eosinophilic pneumonia: the photographic negative of pulmonary edema. AJR Am J Roentgenol. 1977 Jan;128(1):1-13.
• Jeong YJ, Kim KI, Seo IJ, Lee CH, Lee KN, Kim KN, Kim JS, Kwon WJ. Eosinophilic lung diseases: a clinical, radiologic, and pathologic overview. Radiographics. 2007 May-Jun;27(3):617-37.