Reversed halo sign: high-resolution CT scan findings in 79 patients.
BACKGROUND
The purpose of this study was to evaluate the high-resolution CT (HRCT) scan findings of patients with the reversed halo sign (RHS) and to identify distinguishing features among the various causes.


METHODS
Two chest radiologists reviewed the HRCT scans of 79 patients with RHS and determined the CT scan findings by consensus. We studied the morphologic characteristics, number of lesions, and presence of features associated with RHS.


RESULTS
Forty-one patients presented with infectious diseases (paracoccidioidomycosis, TB, zygomycosis, invasive pulmonary aspergillosis, Pneumocystis jiroveci pneumonia, histoplasmosis, cryptococcosis), and 38 presented with noninfectious diseases (cryptogenic organizing pneumonia, pulmonary embolism, sarcoidosis, edema, lepidic predominant adenocarcinoma [formerly bronchiolo-alveolar carcinoma], granulomatosis with polyangiitis [Wegener]). The RHS walls were smooth in 58 patients (73.4%) and nodular in 21 patients (26.6%). Lesions were multiple in 40 patients (50.6%) and single in 39 patients (49.4%).


CONCLUSIONS
The presence of nodular walls or nodules inside the halo of the RHS is highly suggestive of granulomatous diseases.
Federal University of Rio de Janeiro, Rio de Janeiro. Electronic address: edmarchiori@gmail.com.
Edson
E
Marchiori
Federal University of Rio de Janeiro, Rio de Janeiro.
Gláucia
G
Zanetti
Federal University of Parana, Curitiba.
Dante Luiz
DL
Escuissato
Federal University of Parana, Curitiba.
Arthur Soares
AS
Souza
São Paulo Federal University, São Paulo, Brazil.
Gustavo
G
de Souza Portes Meirelles
Federal University of Rio de Janeiro, Rio de Janeiro.
Joana
J
Fagundes
Faculty of Medicine of São José do Rio Preto, São José do Rio Preto, São Paulo, Brazil; Ottawa Hospital, Ottawa, ON, Canada.
Carolina Althoff
CA
Souza
Federal University of Rio de Janeiro, Rio de Janeiro.
Bruno
B
Hochhegger
University of Texas MD Anderson Cancer Center, Houston, Texas.
Edith M
EM
Marom
University of Texas MD Anderson Cancer Center, Houston, Texas.
Myrna C B
MCB
Godoy
D000328:Adult; D000368:Aged; D000465:Algorithms; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000000981:diagnostic imaging; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D055613:Multiple Pulmonary Nodules / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed