INTRODUCTION: Several radiographic findings have been described in patients with cryptogenic organizing pneumonitis (COP). We report a case of COP exhibiting a fairy ring sign on high resolution computed tomography (HRCT). This is the first reported case of a fairy ring sign in a patient with COP.
CASE PRESENTATION: A 54-year-old African American female with no significant past medical history presented with a productive cough for 3 weeks and dyspnea. This patient originally presented to the ER approximately 3 weeks earlier at the onset of her cough and a chest radiograph at that time showed infiltrates in the right lower lobe. She was diagnosed with community-acquired pneumonia. A 5 day course of azithromycin was prescribed, but her pulmonary symptoms failed to improve. Physical examination was unremarkable except for fine crackles at the right base. A CT chest revealed a ring-shaped opacity in the right lower lobe lesion with normal lung parenchyma in the center. A bronchoscopy with transbronchial biopsies showed organizing pneumonia with no evidence of an alternative diagnosis. Systemic steroids were initiated and slowly tapered over 6 months with marked improvement in symptoms and radiographic abnormalities
DISCUSSION: The typical imaging features of COP on chest radiographs consist of patchy alveolar opacities, usually bilateral, which may be migratory. They usually predominate in the lower lung zones. On HRCT, the most common finding of COP is bilateral patchy areas of densities, which varies from ground-glass opacities to consolidation. These opacities are predominantly subpleural or in peribronchovascular distribution. Their size ranges from a few centimeters to an entire lobe.1 The reverse halo sign is characterized by central ground glass opacity surrounded by a rim of dense air space consolidation and is seen in 10-15% of patients with COP on HRCT.2 Correlative studies with pathological samples from lungs with reverse halo signs have shown that the central ground-glass opacity corresponds histopathologically to the area of alveolar septal inflammation and cellular desquamation with a small amount of granulation tissue in the terminal air spaces, whereas the ring-shaped or crescentic peripheral air-space consolidation corresponds to the area of intraluminal organizing pneumonia and fibrosis within the distal air spaces. A fairy ring on high-resolution CT (HRCT) scan was first described by Marlow et.al. in a patient with alveolar sarcoidosis.3 It is defined as central normal lung parenchyma surrounded by ring or crescentic-shape, dense air-space consolidation. The fairy ring sign has not been previously reported as a radiographic manifestation of COP. Although the fairy ring sign has not been studied pathologically, it likely represents a central area of normal lung parenchyma surrounded by a rim of consolidation and fibrosis. Therefore, it is plausible that the fairy ring sign and reverse halo sign could be observed with inflammatory lung diseases where the resolution of the inflammation may not leave residual permanent lung destruction or fibrosis. COP and sarcoidosis are two such diseases. We suspect that there is minimal distinction between the fairy ring sign and the reverse halo sign; it is likely that the former represents circumferential inflammation that has expanded outward leaving normal lung in its wake whereas the latter represents circumferential inflammation that has left lung parenchyma in its center in the process of complete healing.
CONCLUSIONS: 1. The fairy ring sign and reverse halo sign are representative of a pattern of developing lung inflammation that is not pathognomonic for a specific disease process. 2. These radiographic patterns may occur with diseases that cause alveolar inflammation without damage or fibrosis i.e COP,sarcoidosis.
Reference #1 Bouchardy LM, Kuhlman JE, Ball WC, Jr., Hruban RH, Askin FB, Siegelman SS. Ct findings in bronchiolitis obliterans organizing pneumonia (boop) with radiographic, clinical, and histologic correlation. J Comput Assist Tomogr 1993;17:352-357.
Reference #2 Akira M, Yamamoto S, Sakatani M. Bronchiolitis obliterans organizing pneumonia manifesting as multiple large nodules or masses. AJR Am J Roentgenol 1998;170:291-295.
Reference #3 Marlow TJ, Krapiva PI, Schabel SI, Judson MA. The "Fairy ring": A new radiographic finding in sarcoidosis. Chest 1999;115:275-276.
DISCLOSURE: The following authors have nothing to disclose: Hiren Mehta, Luca Paoletti, Nicholas Pastis, Marc Judson
No Product/Research Disclosure Information