We report the case of a 63-year-old man, non-smoker, who presented in the emergency room with acute onset of dyspnea and fever. A chest X-ray showed a roughly nodular opacity in the right perihilar region (Fig. 1A), so the patient was admitted to a medical department with a diagnosis of pneumonia. Due to clinical worsening despite broad-spectrum antibiotic coverage, a chest CT was performed which showed a reversed halo sign (RHS) in the right lung (Fig. 1B). This prompted an extensive investigation including a CT pulmonary angiography that demonstrated the presence of a thrombus in the right main pulmonary artery (Fig. 1C).
The RHS or atoll sign is characterized by a central ground-glass opacity surrounded by denser air-space consolidation in the shape of a crescent or a ring.1
Although it was initially considered a pathognomonic sign for organizing pneumonia, this manifestation has been associated with a wide range of infectious and non-infectious diseases, including pulmonary embolism (PE).1 In the latter, the RHS seems to correspond to pulmonary infarction in PE2 and diagnosis should be based on clinical and radiological findings.
Please cite this article as: Nascimento LM, Fernandes A. Signo del halo invertido: ¿qué hay debajo?. Arch Bronconeumol. 2016;52:390.
