Reverse halo sign

Abstract

Can you identify the radiological sign on HRCT?A 14‑year‑old female patient presented with fever associated with dry cough of 8 months duration. There was no history of hemoptysis, wheezing, chest pain, loss of weight, or loss of appetite. Sputum smears for acid‑fast bacilli were negative.The posteroanterior chest radiograph [Figure 1] showed multiple confluent alveolar opacities in both lungs with lower zone predominance. High‑resolution computed tomographic(HRCT) scan of the thorax demonstrated multifocal variable‑sized nodular opacities, and many of the nodular and consolidated areas showed central lucency or central ground‑glass opacity [Figure 2]. There was no mediastinal lymph node enlargement.Computed tomography (CT)‑guided biopsy confirmed the diagnosis of cryptogenic organizing pneumonia(COP).