Hemosiderin cap sign

Last revised by Dr Maxime St-Amant on 18 Feb 2018

The hemosiderin cap sign refers to an MR imaging feature in some spinal tumors where a cap of T2 hypointense hemosiderin is above and/or below the tumor due to previous hemorrhage. 

It is most often associated with spinal cord ependymomas (20-33% of cases) 1. It may also be seen in hemangioblastomas and paragangliomas and therefore it is suggestive  but not pathognomonic of ependymoma

In addition, larger cavernous malformations of the spine may appear to lack a complete hemosiderin ring where they reach the pial surface, and thus develop a hemosiderin cap. 

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Cases and figures

  • Case 1: ependymoma
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  • Case 2: paraganglioma
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  • Case 3: cavernoma
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