The halo sign: HRCT findings in 85 patients

Abstract

Objective: The halo sign consists of an area of ground-glass opacity surrounding pulmonary lesions on chest CT scans. We compared immunocompetent and immunosuppressed patients in terms of halo sign features and sought to identify those of greatest diagnostic value. Methods: This was a retrospective study of CT scans performed at any of seven centers between January of 2011 and May of 2015. Patients were classified according to their immune status. Two thoracic radiologists reviewed the scans in order to determine the number of lesions, as well as their distribution, size, and contour, together with halo thickness and any other associated findings. Results: Of the 85 patients evaluated, 53 were immunocompetent and 32 were immunosuppressed. Of the 53 immunocompetent patients, 34 (64%) were diagnosed with primary neoplasm. Of the 32 immunosuppressed patients, 25 (78%) were diagnosed with aspergillosis. Multiple and randomly distributed lesions were more common in the immunosuppressed patients than in the immunocompetent patients (p < 0.001 for both). Halo thickness was found to be greater in the immunosuppressed patients (p < 0.05). Conclusions: Etiologies of the halo sign differ markedly between immunocompetent and immunosuppressed patients. Although thicker halos are more likely to occur in patients with infectious diseases, the number and distribution of lesions should also be taken into account when evaluating patients presenting with the halo sign.

Tomographic assessment of thoracic fungal diseases: a pattern and signs approach

“…Its occurrence is usually transient, being more common in the early stages of the disease ( 29 ) . For the differential diagnosis, it should be noted that thickness of the ground-glass halo is often greater in infectious conditions ( 30 ) .…”

COVID-19 pneumonia presenting as a single pulmonary nodule in a kidney transplant recipient: A case report and literature review

“…The CT halo sign has been typically seen in fungal infections, vasculitis, organizing pneumonia, and viral infections [19] . The most common cause of CT halo sign in immunocompromised and immunocompetent patients are pulmonary aspergillosis and malignancy [ [20] , [21] ]. Solid nodules with a peripheral halo of ground glass are reported in a range of 0%-26% in COVID-19 patients and are considered as an atypical imaging presentation so far [22] , [23] , [24] , [25] , [26] .…”

The halo sign as a chest computed tomography finding of COVID-19

“…So far, numerous other etiologies with this tomography presentation have been already described. (4,8,9) In immunocompromised patients, in addition to angioinvasive aspergillosis (most frequent in neutropenic individuals), the possibility of Kaposi sarcoma should be also considered in HIV-positive patients with low CD4 T-cell counts. However, in immunocompromised patients, the halo sign can be found in primary adenocarcinoma of the lung (mainly when there is lepidic component), metastasis (specially associated with hemorrhagic component), and in other inflammatory and infectious conditions such as granulomatosis with polyangiitis, organizing pneumonia, some bacterial, fungi, and viral infections.…”

“…However, in immunocompromised patients, the halo sign can be found in primary adenocarcinoma of the lung (mainly when there is lepidic component), metastasis (specially associated with hemorrhagic component), and in other inflammatory and infectious conditions such as granulomatosis with polyangiitis, organizing pneumonia, some bacterial, fungi, and viral infections. (4,8,9) Although the halo sign constitutes a CT finding with large differential diagnosis and it is rarely found in pneumonias caused by SARS-CoV-2, this CT sign in individuals under COVID-19 investigation can help in this disease diagnosis and management, particularly during the current pandemic.…”