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|LETTERS TO EDITOR
|Year : 2016 | Volume
| Issue : 1 | Page : 185-186
Calcifying pseudoneoplasm of the superior medullary velum: An unusual location for a rare lesion
Lee A Tan1, Sahr Syed2, Leonidas D Arvanitis2, Lorenzo F Munoz1
1 Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA
2 Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
|Date of Web Publication||11-Jan-2016|
Lee A Tan
Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Tan LA, Syed S, Arvanitis LD, Munoz LF. Calcifying pseudoneoplasm of the superior medullary velum: An unusual location for a rare lesion. Neurol India 2016;64:185-6
|How to cite this URL:|
Tan LA, Syed S, Arvanitis LD, Munoz LF. Calcifying pseudoneoplasm of the superior medullary velum: An unusual location for a rare lesion. Neurol India [serial online] 2016 [cited 2020 Feb 27];64:185-6. Available from: http://www.neurologyindia.com/text.asp?2016/64/1/185/173619
A 45-year old previously healthy man presented with daily headaches along with worsening vision and diplopia over the past 6 months. His physical examination was unremarkable except for a mild left abducens nerve palsy. Magnetic resonance imaging (MRI) of the brain revealed a lobulated, heterogeneously enhancing mass arising from the superior medullary velum measuring 2.0 × 1.9 × 1.6 cm [Figure 1]a and [Figure 1]b. The mass appeared hypointense on T1- and T2-weighted imaging; however, there were a few foci of hyperintensity in the ventral aspect of the mass on T1-weighed imaging that showed signal suppression on short tau inversion recovery (STIR) sequence, suggesting some fatty content. There was no increased perfusion on MR perfusion sequence. Given the patient's progressive symptoms and the need for a definitive diagnosis, surgical resection of the mass was deemed necessary after an in-depth discussion with the patient and his family. The lesion was successfully resected via a suboccipital craniotomy without any complication [Figure 1]c. Intraoperatively, the lesion was noted to have a significant calcified component along with some lipomatous tissue. Pathological examination of the mass demonstrated predominantly hypocellular basophilic calcified matrix arranged in a lobular pattern [Figure 1]d, surrounded by palisading epithelioid cells [Figure 1]e. A chondroid matrix was present along with abundant fibrovascular stroma and a focal area of osseous metaplasia [Figure 1]f. The diagnosis of calcifying pseudoneoplasm of the neuraxis (CAPNON) was made. At the 3-month follow-up visit, the patient was stable neurologically with only mild diplopia persisting.
|Figure 1: Preoperative axial (a) and sagittal (b) T1-weighted MRI with contrast demonstrating a heterogeneously enhancing mass arising from the superior medullary velum; postoperative axial T1-weighted MRI with contrast (c) demonstrating the removal of the mass, with minimal residual tissue; pathological examination of the mass demonstrated predominantly hypocellular basophilic calcified matrix arranged in a lobular pattern (d), surrounded by palisading epithelioid cells (e); a chondroid matrix was also present with abundant fibrovascular stroma and a focal area of osseous metaplasia (f)|
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CAPNONs are rare, benign lesions first described by Rhodes et al., in 1978. There are less than 50 cases of CAPNON reported in literature since its first description., CAPNONs can occur in an intra-axial or extra-axial location in both the brain and the spinal cord, but its occurrence in the posterior fossa is extremely rare. The exact etiology of these lesions is still unknown  but it is thought to be due to a reactive process based on the associated granulomatous inflammation typically surrounding the calcification, that is evident on pathological examination., The presenting symptoms largely depend on the location of the lesion.
Many of these lesions are discovered incidentally, whereas others may present with headache, seizures, pain, and focal neurological deficits. Imaging characteristics of CAPNONs include dense calcification on computed tomography (CT) and low signals on T1- and T2-weighted imaging consistent with calcification, with a variable enhancement pattern. CAPNONs tend to have an excellent prognosis after surgical resection with low recurrence rates., Histological examination typically reveals a polymorphous pattern of basophilic acellular matrix, coarse fibrillar elements, variable amounts of fibrous stroma, calcium deposition, osseous metaplasia, or palisading spindle and/or polygonal cells. They are usually positive for vimentin and epithelial membrane antigen (EMA), and negative for S100 and glial fibrillary acidic protein (GFAP).
Our case highlights the fact that although very rare, CAPNONs can occur in the posterior fossa and must be kept in the differential diagnosis when a calcified mass is encountered in this location. Complete surgical removal of this lesion confers an excellent prognosis.
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There are no conflicts of interest.
| » References|| |
Rhodes RH, Davis RL. An unusual fibro-osseous component in intracranial lesions. Hum Pathol 1978;9:309-19.
Stienen MN, Abdulazim A, Gautschi OP, Schneiderhan TM, Hildebrandt G, Lücke S. Calcifying pseudoneoplasms of the neuraxis (CAPNON): Clinical features and therapeutic options. Acta Neurochir (Wien) 2013;155:9-17.
Kerr EE, Borys E, Bobinski M, Shahlaie K. Posterior fossa calcifying pseudoneoplasm of the central nervous system. J Neurosurg 2013;118:896-902.