Reply:
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* A.H. Aiken
* T. Tihan
* C. Glastonbury

We appreciate the interest of Dr Pereira and colleagues, their insightful comments, and case presentation. As aptly described in their letter and mentioned in our article,1 calcified choroid plexus papillomas, particularly in young patients, are among the differential considerations of calcifying pseudoneoplasm of the neuraxis (CAPNON). This case illustrates that the rare ossified choroid plexus papilloma can even more closely mimic CAPNON on MR and CT imaging. Although the imaging appearance can be similar, the pathologic appearance is distinctly different between these 2 entities. As Dr Pereira and colleagues noted, the critical difference is the absence of an epithelial component in CAPNON and the unique basophilic material distinct from osseous metaplasia.

## Reference

1.  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;30:1256–60
    
    [Abstract/FREE Full Text](http://www.ajnr.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiYWpuciI7czo1OiJyZXNpZCI7czo5OiIzMC82LzEyNTYiO3M6NDoiYXRvbSI7czoxOToiL2FqbnIvMzEvNi9FNTMuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

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