Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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January 30, 2012
Calcifying Pseudoneoplasm of the Neural Axis (CAPNON)
- CAPNON, also known as fibro-osseous lesion of the nervous system, is a non-neoplastic process which is proliferative and reparative.
- It is a rare entity with pathognomonic features of discrete, hypocellular nodule(s) of coarsely fibrillar, basophilic matrix with palisading of nuclei at the perimeter. The amount of calcification and ossification varies.
- Both intra- and extra-axial lesions occur, usually extra-axial, rarely completely intraosseous. Most are solitary, but can be multiple. Lesion size varies from microscopic to 10cm in diameter.
- Most common location is the epidural space of spine. All levels of the spine (cervical, thoracic, lumbar) can be affected.
- Key Diagnostic Features: CT: variable amount of calcification; MRI: hypointense on T1 and T2, minimal linear rim or serpiginous internal enhancement, limited to no edema
- DDx: Psammomatous meningioma, primary or metastatic tumors with calcification, and vascular malformations
- Rx: Surgical removal
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