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Table of Contents
CASE REPORT
Year : 2020  |  Volume : 23  |  Issue : 6  |  Page : 811-813
 

Calcified pseudoneoplasm of the neuraxis (CAPNON)–A rare cause for temporal lobe epilepsy: Not all warrant a surgical intervention


Department of Radiology, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, Tamil Nadu, India

Date of Submission10-Sep-2019
Date of Acceptance15-Sep-2019
Date of Web Publication18-Dec-2020

Correspondence Address:
Dr. Prashanth Raghu
Department of Radiology, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aian.AIAN_462_19

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   Abstract 

Epilepsy is a common neurological condition with varied etiological causes, with temporal lobe epilepsy being the most common. Among the varied etiologies of temporal lobe epilepsy, mesial temporal sclerosis is an important one and it presents as intractable epilepsy. However, we describe here a case of intractable temporal lobe epilepsy with a rather rare etiology, calcifying pseudo neoplasm of neuraxis (CAPNON) syndrome. CAPNON is a rare benign lesion that can occur anywhere in the central nervous system. The thought process till date is to excise any intracranial space occupying lesion to relieve pressure and for a better prognosis, which is not questionable. However, we feel in case of CAPNON, wait and watch protocol can be used to a better effect with radiological and clinical follow-up. Above all surgical excision was primarily done due to imaging confusion over CAPNON and this article comes up with few key findings to clinch the radiological diagnosis of CAPNON.


Keywords: Calcifying pseudo neoplasm of neuraxis, cavernoma, epilepsy, pseudoneoplasm


How to cite this article:
Raghu P, Jeevanandham B, Ramachandran R, Ralph J, Paneerselvam P. Calcified pseudoneoplasm of the neuraxis (CAPNON)–A rare cause for temporal lobe epilepsy: Not all warrant a surgical intervention. Ann Indian Acad Neurol 2020;23:811-3

How to cite this URL:
Raghu P, Jeevanandham B, Ramachandran R, Ralph J, Paneerselvam P. Calcified pseudoneoplasm of the neuraxis (CAPNON)–A rare cause for temporal lobe epilepsy: Not all warrant a surgical intervention. Ann Indian Acad Neurol [serial online] 2020 [cited 2021 Jan 25];23:811-3. Available from: https://www.annalsofian.org/text.asp?2020/23/6/811/271743



   Introduction Top


Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare entity with only 90 cases being reported in literature till date. Among the reported 90 cases, 54 (60%) are intracranial and 36 (40%) are intraspinal lesions.[1] It was first identified by Miller and erroneously reported as fibro-osseous lesion in 1922. It has been synonymously termed as brain stones, fibro-osseous lesions, and calcifying pseudo tumors.[2] In 1978, it was reported as a distinct entity by Rhodes.[2],[3],[4] If intracranial, it can be either intra or extra-axial in location.[2],[5] This entity mimics many calcifying intra-axial lesions like ganglioglioma, oligodendroglioma, cavernous malformation, and infection like tuberculosis. Hence, CAPNON should always be considered in the list of differential diagnosis for calcifying intra-axial lesions.[6] Few patients have presented with hallucinations and partial seizures. Here, we illustrate a case presenting with intractable temporal lobe epilepsy and eventually diagnosed as CAPNON on imaging which was conservatively managed with a good clinical outcome.


   Case History Top


A male patient came to emergency room with five episodes of seizures since morning involving the right upper and lower limbs with secondary generalization. He was a known case of seizure disorder for the past 5 years and on anti-epileptic medication which includes eptoin and valproate. Based on clinical symptoms, the patient was referred for CT examination.

Non-contrast CT scan revealed multiple thick amorphous calcifications involving the right gangliocapsular region involving the genu and posterior limb of internal capsule, lentiform nucleus, right hippocampus, and right peduncle of midbrain [Figure 1]a and [Figure 1]b. The patient was further evaluated with MRI with intravenous Gadolinium contrast. The MRI scan revealed an ill-defined intra-axial predominantly T2 hyperintense/T1 hypointense lesion involving the right thalamo capsular region, right medial temporal lobe, and the right peduncle of midbrain [Figure 2]a and [Figure 2]b. Multiple discrete areas of blooming noted within the lesion on GRE [Figure 3] with magnitude and phase sequences of SWI showed features suggestive of calcification [Figure 4]a and [Figure 4]b. Post-contrast T1-weighted axial and sagittal images shows minimal ill-defined discrete enhancement [Figure 5]a and [Figure 5]b.
Figure 1: A man with seizures, (a) axial and (b) coronal sections of CT images shows multiple chunky parenchymal calcifications (star) in the right gangliocapsular region involving the genu and posterior limb of internal capsule, lentiform nucleus, right hippocampus, and right peduncle of midbrain

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Figure 2: A man with seizures, (a) T1W and (b) T2W MR images shows a T1 hypointense (right arrow) and a T2 hyperintense (left arrow) lesion in the right thalamocapsular region with mild perilesional surrounding edema (right curved arrow)

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Figure 3: A man with seizures, gradient echo image shows multiple foci of blooming within the lesion (right arrow), suggestive of calcification

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Figure 4: A man with seizures, Magnitude (a) and Phase (b) sequences of SW images shows the lesion with blooming (star) in magnitude sequence and bright spot (Arrow head) in phase sequence, thus denoting areas of calcifications within the lesion

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Figure 5: A man with seizures, T1 post-contrast (a) axial and (b) sagittal MR images shows the lesion with areas of minimal enhancement upon contrast administration (right arrow)

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Based on the imaging findings, a diagnosis of CAPNON was made and the patient was advised to continue the anti-epileptic drugs with regular follow-up. On follow-up, EEG was done and found normal. The patient was symptomatically better now. Hence, surgical plan was withheld.


   Discussion Top


CAPNON is a rare tumor of the central nervous system. A hypothesis has been suggested that CAPNON may develop as a healing response to a wide range of eliciting factors, which could explain the variations in histopathologic features. Even though the histopathologic features of CAPNON are not clearly understood, a reactive process over a hamartomatous process has been favored.[2],[7],[8] Interestingly, this reactive process involved in the calcifying pseudoneoplasm is not only constrained to the neuraxis. It can also occur at different other sites, including pleura, breast, and mediastinum.[9]

No sex or age predominance has been mentioned in most of the published articles, however the lesions can occur at any age between 6 and 83 years.[2],[6],[8] The most common symptoms in intracranial lesions are headache and seizure with only few cases being discovered incidentally.[2],[8] Symptoms, when present, are variable and are related to local mass effect, rather than invasive growth. Seizure was the commonest symptom in supratentorial CAPNON (17/36 cases; 47.2%). The seizure types were generalized tonic--clonic seizure (GTCS) in 7 cases (41.1%), focal impaired awareness seizure (FIAS) in 4 cases (23.5%), focal aware seizure (FAS) in 2 cases (11.8%), and not described in 4 cases.[1] The lesions are typically sporadic, with few exceptions that have occurred in association with meningioangiomatosis in patients with type 2 neurofibromatosis[9],[10] and low-grade glioma.[10]

On CT, generally CAPNON shows an area of solid calcification while on MR imaging the lesions appear hypointense on T1- and T2-weighted sequences.[8] Post-contrast the lesions shows minimal linear internal or rim enhancement.[8] Contrary in our case, the lesion showed areas of T2 hyperintensity, probably because of the presence of chondromyxoid matrix within the areas of calcifications. Perilesional vasogenic edema is not commonly reported and is unexpected in benign lesion.[8] Grabowski et al., in his study, reported vasogenic edema could be because of seizures rather than CAPNON.[8] Similarly, in our case, perilesional edema was present secondary to seizures rather than CAPNON as proposed by Grabowski et al.

The typical histopathological features of CAPNON are (1) presence of palisading spindle to epithelioid cells; (2) presence of chondromyxoid matrix in a nodular pattern; (3) amorphous calcification, psammoma bodies, and osseous metaplasia; (4) foreign-body reaction with giant cells surrounding the calcified region; (5) fibroblastic proliferation.[2],[3],[11] These pathological presentations are not evident in each case and some lesions may not show all of the above features.[2],[11] In our case, the patient was conservatively managed with anti-epileptic medications and is on regular follow-up. Earlier treatment has prevented the patient suffering from future complications like deterioration of memory.

Acknowledgements

The author would like to thank his parents, friends, and teachers for their moral support.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Tanoue Y, Uda T, Nakajo K, Nishijima S, Sasaki T, Ohata K. Surgically treated intracranial supratentorial calcifying pseudoneoplasms of the neuraxis (CAPNON) with drug-resistant left temporal lobe epilepsy: A case report and review of the literature. Epilepsy Behav Case Rep 2019;11:107-14.  Back to cited text no. 1
    
2.
Zerehpoosh FB, Samadian M, Azhari VS, Barangi M, Ebrahimzadeh K, Heidary M. A case report of calcifying pseudoneoplasm of the neuraxis: An incidental finding after a car accident. Turk Patoloji Derg 2018;34:265-8.  Back to cited text no. 2
    
3.
Fletcher AM, Greenlee JJ, Chang KE, Smoker WR, Kirby PA, O'Brien EK. Endoscopic resection of calcifying pseudoneoplasm of the neuraxis (CAPNON) of the anterior skull base with sinonasal extension. J Clin Neurosci 2012;19:1048-9.  Back to cited text no. 3
    
4.
Rhodes RH, Davis RL. An unusual fibro-osseous component in intracranial lesions. Hum Pathol 1978;9:309-19.  Back to cited text no. 4
    
5.
Mohapatra I, Manish R, Mahadevan A, Prasad C, Sampath S, Shankar SK. Shankar, Calcifying pseudoneoplasm (fibro osseous lesion) of neuraxis (CAPNON)—A case report. Clin Neuropathol 2010;29:223-6.  Back to cited text no. 5
    
6.
Aiken AH, Akgun H, Tihan T, Barbaro N, Glastonbury C. Calcifying pseudoneoplasms of the neuraxis: CT, MR imaging, and histologic features. Am J Neuroradiol 2009;30:1256-60.  Back to cited text no. 6
    
7.
Nonaka Y, Aliabadi HR, Friedman AH, Odere FG, Fukushima T. Calcifying pseudoneoplasms of the skull base presenting with cranial neuropathies: Case report and literature review J Neurol Surg Rep 2012;73:41-7.'  Back to cited text no. 7
    
8.
Merola J, Jain A, Ziad F, Hussain Z. Calcified Pseudoneoplasm of the Neuraxis (CAPNON): A lesson learnt from a rare entity. J Neurol Neurosci 2016. DOI: 10.21767/2171-6625.1000121.  Back to cited text no. 8
    
9.
Donev K, Scheithauer BW. Pseudoneoplasms of the nervous system. Arch Pathol Lab Med 2010;134:404-16.  Back to cited text no. 9
    
10.
Higa N, Yokoo H, Hirano H, Yonezawa H, Oyoshi T, Goto Y, et al. Calcifying pseudoneoplasm of the neuraxis in direct continuity with a low-grade glioma: A case report and review of the literature. Neuropathology 2017;37:446-51.  Back to cited text no. 10
    
11.
Aiken AH, Akgun H, Tihan T, Barbaro N, Glastonbury C. Calcifying pseudoneoplasms of the neuraxis: CT, MR imaging, and histologic features. Am J Neuroradiol 2009;30:1256-60.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]



 

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