Sack of marbles sign (dermoid cyst)

Last revised by Dr Mohamed Saber on 22 Oct 2020

The sack of marbles sign, also known as the marbles in a bag sign, refers to aggregations of multiple small globules of fat within a cyst mimicking marble spheres within a sack. They appear hyperechoic on ultrasound, fat attenuation on CT, and high signal on T1WI and T2WI on MRI. It is considered highly suggestive of a dermoid cyst in the head and neck region ​1-7. The term has also been used to describe ovarian dermoid cysts 8,9, although the floating balls sign is a more commonly used descriptor in this region.

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Cases and figures

  • Case 1: Orbital dermoid cyst - sack of marbles sign
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