Superior extraconal orbital fat hyperintensityin pediatric population: a potential diagnostic pitfall

With the increasing use of magnetic resonance imaging (MRI) in children, radiologists frequently encounter incidental findings that may mimic pathology. One such underrecognized finding is T2-weighted hyperintensity in the superior extraconal orbital fat, which is occasionally mistaken for an infiltrative or neoplastic process.

Our objective was to characterize the imaging appearance, prevalence, and clinical associations of superior extraconal orbital fat T2 hyperintensity in pediatric MRI.

We conducted a retrospective study of 143 pediatric patients (mean age 7.2±5.1 years) who underwent brain MRI with an orbit-specific protocol between 2015 and 2022. Patients were grouped based on the presence or absence of bilateral papilledema and whether imaging was performed under general anesthesia. Clinical data were extracted from the electronic medical records. Three neuroradiologists reviewed images for the presence of a hyperintense signal along the superior extraconal orbital fat. Interobserver agreement was calculated using Fleiss' kappa. Univariate and multivariable logistic regression analyses were performed to assess associations with age, anesthesia, gender, and magnet strength.

Symmetric T2-hyperintense bands along the superior extraconal orbital fat were observed in 45.5% of patients. The finding was more common in younger children (4.4±3.9 years vs. 9.6±4.8 years; P<0.001). Multivariate analysis showed a significant negative correlation with age (P<0.001) and a positive correlation with papilledema (P=0.012), but no independent association with gender, anesthesia, or magnet strength. The hyperintensity was non-enhancing or only subtly enhancing. Clinical follow-up demonstrated no subsequent orbital or infiltrative pathology in the majority of patients, and most patients without documented follow-up underwent ambulatory MRI for evaluation of strabismus, which showed no evidence of infiltrative or other orbital disease.

Superior extraconal orbital fat T2 hyperintensity is a relatively common, likely non-pathologic MRI finding in pediatric patients, particularly in younger children, and the apparent association with anesthesia likely reflects age-related confounding. Awareness of this benign appearance may help avoid diagnostic confusion and prevent unnecessary workup or intervention.