doi: 10.3174/ajnr.A1505
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American Journal of Neuroradiology 30:1256-1260, June-July 2009
© 2009 American Society of Neuroradiology
BRAIN
Calcifying Pseudoneoplasms of the Neuraxis: CT, MR Imaging, and Histologic Features
a Departments of Radiology, University of California, San Francisco, Calif
b Pathology, University of California, San Francisco, Calif
c Neurosurgery, University of California, San Francisco, Calif
Please address correspondence to Ashley H. Aiken, MD, Department of Radiology, San Francisco General Hospital, 1001 Potrero Ave, Room 1x55, San Francisco, CA 94110; e-mail: Ashley.aiken{at}radiology.ucsf.edu
BACKGROUND AND PURPOSE: Non-neoplastic, calcified, fibro-osseous lesions known as "calcifying pseudoneoplasms of the neuraxis" (CAPNON) are rare and can occur anywhere within the neuraxis. The radiologic and histopathologic characteristics of this unusual entity are not well understood. We present the largest series reviewing the MR imaging features of CAPNON.
MATERIALS AND METHODS: The MR and CT imaging features in 4 patients with a pathologic diagnosis of "calcifying pseudoneoplasms of the neuraxis" were retrospectively reviewed. A neuropathologist also analyzed the histopathologic features for typical and atypical patterns.
RESULTS: Imaging features were strikingly similar for all 4 patients. All lesions appeared T1 and T2 hypointense without vasogenic edema. All tumors had dense calcification, and 3 tumors showed minimal linear internal or rim enhancement on MR imaging.
CONCLUSIONS: CAPNON may mimic more common vascular malformations or neoplasms and are often not considered in the differential diagnosis of calcified lesions. CAPNON should be included in the differential diagnosis of a calcified mass with marked T1 and T2 hypointensity and limited to no enhancement. Careful CT and MR imaging evaluation can suggest this entity, and this preoperative recognition may help subsequent management decisions.