Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare non-neoplastic, non-inflammatory heavily calcified discrete intraparenchymal or extra-axial lesions of CNS. The most common location is temporal region.
They usually asymptomatic and found incidentally but sometimes they can present with a seizure.
CAPNON lesions demonstrate extensive calcifications and a chondromyxoid matrix with an amorphous quality and fibrovascular stroma. The spindle and epithelioid cells surrounding the matrix showed positive staining with antibodies against epithelial membrane antigen (EMA).
Although the typical histopathologic features can be observed in most cases, some may be unusual and may be confused with calcified meningioma or tumoral calcinosis.
Can be seen a heavily calcified well-defined leptomeningeal or parenchymal mass.
Typical signal characteristics are those of calcium:
- T1: iso to hypointense
- T2: low signal on FLAIR and T2
- T1 C+ (Gd): varies from none to moderate enhancement
- T2*: mild blooming
CAPNON should be considered in the imaging differential diagnosis of a heavily calcified lesion in neuroaxis. It is important to consider this entity to avoid aggressive surgical intervention.
- 1. Aiken AH, Akgun H, Tihan T et-al. Calcifying pseudoneoplasms of the neuraxis: CT, MR imaging, and histologic features. AJNR Am J Neuroradiol. 2009;30 (6): 1256-60. doi:10.3174/ajnr.A1505 - Pubmed citation
- 2. Stienen MN, Abdulazim A, Gautschi OP et-al. Calcifying pseudoneoplasms of the neuraxis (CAPNON): clinical features and therapeutic options. Acta Neurochir (Wien). 2013;155 (1): 9-17. doi:10.1007/s00701-012-1502-2 - Pubmed citation