Presentation
Painless right orbital swelling since childhood.
Patient Data
There is a well-defined right orbital cystic mass of supraocular location with heterogeneous hypoechoic echotexture containing numerous small echogenic areas giving the typical sack of marbles sign. The video shows the mobile content of the cyst.
There is a well-defined right orbital mass of extraconal supraocular location, measuring 28 x 25 x 18 mm. Il elicits a homogeneous high signal on T1/T2 and FLAIR, attenuated on fat sat sequences with no enhancement following IV contrast. A mass effect is noted on the globe and superior rectus muscle which are displaced inferiorly and lacrymal gland which is displaced laterally.
Case Discussion
Ultrasound and MRI features are highly suggestive of an orbital dermoid cyst with a "sack of marbles sign"
The "sack of marbles sign", also known as the marbles in a bag sign, corresponds to aggregations of multiple small globules of fat within a cyst mimicking marble spheres within a sack. They appear hyperechoic on ultrasound within the hypoechoic content of the cyst, fat attenuation on CT, and high signal on T1WI and T2WI on MRI. It is considered highly suggestive of a dermoid cyst.
Additional contributor: C. Boukaaba, MD