CT halo sign in pulmonary metastases from mucinous adenocarcinoma of the pancreas

The CT halo sign was first described in immunocompromised patients with inv asive pulmonary aspergillosis. Although the halo sign was originally though t to be specific for invasive pulmonary aspergillosis, it has been reported in a wide variety of pulmonary abnormalities in both immunocompromised and immunocompetent patients. We report a case of mucinous adenocarcinoma of t he pancreas metastatic to the lungs in which there were multiple pulmonary nodules showing the halo sign, This case further illustrates the nonspecifi c nature of the CT halo sign and the need to consider malignancy as a cause in immunocompetent patients.