Hemosiderin cap sign

Spinal

ependymoma • Ependymoma (cervical cord) - Ganzer Fall bei Radiopaedia

Gaillard, F. Ependymoma (cervical cord). Case study, Radiopaedia.org. (accessed on 22 Oct 2022) https://doi.org/10.53347/rID-19319 • CC by-nc-sa 3.0 (modified)

Spinal

neuroendocrine tumor • Cauda equina neuroendocrine tumor - Ganzer Fall bei Radiopaedia

Gaillard, F. Cauda equina neuroendocrine tumor. Case study, Radiopaedia.org. (accessed on 22 Oct 2022) https://doi.org/10.53347/rID-19546 • CC by-nc-sa 3.0 (modified)

Spinal cord

cavernous malformation • Cervical cord cavernoma - Ganzer Fall bei Radiopaedia

Gaillard F, Cervical cord cavernoma. Case study, Radiopaedia.org (Accessed on 20 Dec 2022) https://doi.org/10.53347/rID-35547 • CC by-nc-sa 3.0 (modified)

Radiopaedia • CC-by-nc-sa 3.0 • de

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) . 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.