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Table of Contents    
CASE REPORT
Year : 2019  |  Volume : 67  |  Issue : 5  |  Page : 1347-1351

Intracranial Myoepithelioma: A Case Report and Review of Literature


1 Department of Pathology, Gleneagles Global Health City; Department of Histopathology, Dr Rela Institute and Medical Centre, Chennai, Tamil Nadu, India
2 Department of Neurosurgery, Gleneagles Global Health City, Institute of Neurosciences and Spinal Disorders; Department of Neurosurgery, MGM Healthcare Multi Super Speciality Hospital, Chennai, Tamil Nadu, India

Date of Web Publication19-Nov-2019

Correspondence Address:
Dr. G Gowripriya
Consultant Histopathologist, Dr Rela Institute and Medical Centre, CLC Works Road, Nagappa Nagar, Chromepet, Chennai - 600 044, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.271273

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 » Abstract 


Intracranial myoepithelial tumors are extremely rare with <10 cases reported outside the sellar region. The authors describe a case of a 43-year-old male patient who presented with headache, numbness in the face, and a dumbbell-shaped lesion in the Meckel's cave clinically and radiologically suggestive of a Schwannoma. The histopathological and immunohistochemical evaluation led to a diagnosis of myoepithelioma. A review of literature reveals that this is only the ninth case of intracranial myoepithelial tumor reported, fifth benign case, and the first to be reported in the Meckel's cave region.


Keywords: Meckel's cave, myoepithelial, myoepithelioma
Key Message: Myoepithelial tumours within the central nervous system are histomorphologically heterogenous tumours, being increasingly described in recent times due to the availability of expanding immunohistochemical panels. These tumours may clinically and radiologically resemble meningiomas/ schwannomas.


How to cite this article:
Gowripriya G, Sridhar K, Vij M. Intracranial Myoepithelioma: A Case Report and Review of Literature. Neurol India 2019;67:1347-51

How to cite this URL:
Gowripriya G, Sridhar K, Vij M. Intracranial Myoepithelioma: A Case Report and Review of Literature. Neurol India [serial online] 2019 [cited 2019 Dec 10];67:1347-51. Available from: http://www.neurologyindia.com/text.asp?2019/67/5/1347/271273




Benign and malignant tumors of myoepithelial origin, originally described in the salivary glands have been increasingly recognized in other sites including breast, skin, lung, and soft tissue. However, they are exceedingly uncommon within the central nervous system excluding the sellar region where they arise from remnants of Rathke's cleft. Less than 10 of such cases arising from the dura and the cerebral parenchyma have been reported in the literature. It is of note that all these cases but one[1] have been reported within the past decade, probably due to their increasing recognition with the help of immunohistochemical markers. We report a rare case of intracranial benign myoepithelioma, which is only the ninth reported case of intracranial myoepithelial tumor and the first at the Meckel's cave.


 » Case Report Top


A 43-year-old male patient presented with left-sided headache, which worsened recently, and was accompanied by numbness over left side of the face and wasting of the left temporalis and left masseter muscles. Magnetic resonance imaging revealed a well-defined, lobulated, dumbbell-shaped, enhancing extra-axial mass lesion with intralesional hemorrhage in the left peripontine cistern extending into the Meckel's cave along the course of trigeminal nerve. With a preoperative diagnosis of left trigeminal schwannoma, the tumor was excised in toto and submitted for histopathology examination.


 » Microscopic Features Top


Histopathological examination revealed a cellular tumor composed of sheets and anastomosing cords of cells embedded in abundant hyalinized and patchy myxoid background [Figure 1], [Figure 2], [Figure 3]. The tumor cells were round, plasmacytoid to polygonal or spindle shaped with mildly to moderately anisomorphic nuclei, granular to coarsely clumped chromatin, inconspicuous nucleoli, and moderate to abundant amounts of eosinophilic to clear cytoplasm [Figure 4] and [Figure 5]. Occasional binucleation was noted. Large cells with abundant clear to vacuolated cytoplasm were also seen [Figure 6] and [Figure 7]. Mitotic activity was 1–2/10 high-power field. The tumor cells diffusely expressed pan cytokeratin, vimentin, and S100, and showed patchy positivity with CK14, 34 betaE12, GFAP, and D240. Occasional cells were positive for p63 [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14] and for smooth muscle actin. Genetic analysis was not done. A diagnosis of myoepithelioma was made.
Figure 1: Sheets and cords of tumor cells (H and E 40× magnification)

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Figure 2: Cells arranged as cords (H and E 40× magnification)

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Figure 3: Cords of tumor cells embedded in hyalinised stroma (H and E 40× magnification)

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Figure 4: Spindle-shaped tumor cells (H and E 100× magnification)

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Figure 5: Polygonal cells in higher magnification (H and E 400× magnification)

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Figure 6: Plasmacytoid and vacuolated cells (H and E 400× magnification)

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Figure 7: Vacuolated cells and hyalinised stromal vessels (H and E 400× magnification)

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Figure 8: Tumour cells positive for PanCytokeratin (H and E 400× magnification)

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Figure 9: Diffuse strong staining with vimentin (H and E 400× magnification)

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Figure 10: Diffuse strong staining with S100 (H and E 400× magnification)

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Figure 11: Patchy positivity with CK14 (H and E 100× magnification)

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Figure 12: Occasional cells positive for myoepithelial marker p63 (H and E 100× magnification)

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Figure 13: Patchy positivity with D240 (H and E 100× magnification)

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Figure 14: Patchy positivity with SMA (H and E 100× magnification)

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 » Discussion Top


Myoepithelial tumors are known for their heterogeneity in terms of histological patterns, cytomorphology, stromal characteristics, and immunophenotype. Apart from the salivary gland where they were originally described, they are now increasingly being recognized in varied anatomical sites including breast, skin, soft tissues, lacrimal gland, tongue, paranasal sinuses, pharynx, larynx, and vulva. The occurrence of myoepithelial tumors within the central nervous system is extremely rare outside the sellar region. Only eight previous cases have been reported within the cranial cavity, of which four were benign and the rest were malignant. Our case is the first to be located in the Meckel's cave and the fifth benign case reported. It is of interest to note that except for the first case reported by Erdogan et al.[1] in 2007, all the other cases have been reported in the past decade. This could be attributed to the use of newer immunohistochemical markers, which help categorize these highly heterogenous appearing tumors.

Intracranial myoepithelial tumors have been reported in patients ranging from 10 months to 48 years of age, both in the extra-axial and intra-axial locations, including the falx region,[1],[2] orbit and dura of middle cranial fossa,[3] cerebellopontine angle,[4] cavernous sinus,[5] and cerebral hemispheres.[6],[7],[8] Hence, the clinical and radiological differential diagnoses have included meningioma, glioma, and schwannoma as was in our case. [Table 1] summarizes the clinical features of intracranial myoepthelial tumors reported in the literature. The histomorphologies described include cords, solid sheets, trabeculae, fascicles, reticular, and adenoid/ductal patterns. The cells are polygonal, rounded, plasmacytoid, spindled, or rhabdoid. The cytoplasmic characteristics include eosinophilic, clear, vacuolated appearances. The stroma in these tumors is also heterogenous, including fibrous, myxoid, chondroid, and hyalinized morphologies. One of the cases also showed osseous metaplasia.[6] Mitotic activity in the malignant cases were as high as 11/10 high-power field with an MIB index of 60%.[5] There are no specific criteria to define these central nervous system tumors as benign or malignant except for the generalized ones.
Table 1: Intracranial myoepithelial tumours: Age and sex distribution, site of origin, and behavior

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As expected of myoepithelial tumors which exhibit a broad capacity of differentiation, the tumor cells are immunopositive for a wide range of epithelial and mesenchymal markers analogous to myoepitheliomas/parachordomas of soft tissue and other sites. Pan cytokeratin, vimentin, and S100 appear to be most consistently positive. Epithelial membrane antigen, smooth muscle actin, and Glial fibrillary acidic protein have been variably expressed. [Table 2] summarizes the histopathological and immunohistochemical features of intracranial myoepithelial tumors.
Table 2: Intracranial myoepithelial tumors: histological and immunohistochemical charecteristics

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About 45% of soft tissue myoepithelial tumors harbor EWSR1 gene translocations, whereas pleomorphic adenoma gene (PLAG-1) mutations are commonly seen in salivary gland myoepitheliomas.[9],[10],[11],[12],[13] Of the previously reported intracranial tumors, genetic studies were done to detect EWSR1 mutations only in two cases,[2] of which only one was positive.

The origin of intracranial myoepithelial tumors is an intriguing question to be answered as the sites of origin have been varied. In and around the sellar region, they seem to arise from salivary gland rests in the posterior pituitary that communicate with the oropharyngeal remnants of Rathke's pouch.[8],[14],[15] Tumors in the middle cranial fossa are thought to arise from ectopic salivary gland tissue in the middle ear.[16] However, their origin from the dura cannot be explained by these theories and could be purported to arise from hypothetical multipotent stem cells within the dura.[1]


 » Conclusion Top


A review of all the described cases of myoepthelial tumors within the central nervous system reveals that these tumors exhibit marked variation in terms of age predilection, sites of origin, architectural patterns, cell morphology, stromal characteristics, and immunoreactivity. Thus, they enter into the differential diagnosis of various tumors like chordomas, chordoid gliomas, chordoid meningiomas, schwannomas, and malignant tumors with cellular pleomorphism. With expanding immuno panels, it is possible that these tumors will be more frequently described in future. Further genetic studies may help in better categorization of the disease. A grading system and criteria for malignancy in the central nervous system may have to be laid in future.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 » References Top

1.
Erdogan S, Rodriguez FJ, Scheithauer BW, Abell-Aleff PC, Rabin M. Malignant myoepithelioma of cranial dura. Am J Surg Pathol 2007;31:807-11.  Back to cited text no. 1
    
2.
Choy B, Pytel P. Primary intracranial myoepithelial neoplasm: A potential mimic of meningioma. Int J Surg Pathol 2016;24:243-7.  Back to cited text no. 2
    
3.
Hayward DM, Yoo D, Lee JM, Wild E, Prabhu VC. Myoepithelioma of the orbital apex and middle cranial fossa: Case report and review of the literature. Neuroophthalmol 2014;38:14-20.  Back to cited text no. 3
    
4.
Vajtai I, Hewer E, Neuenschwander M, Schäfer SC, Kappeler A, Lukes A. Myoepithelioma of the cerebellopontine angle: A previously not documented salivary gland type neoplasm within the cranium. Clin Neuropathol 2013;32;176-82.  Back to cited text no. 4
    
5.
Hong Y, Guo SX, Chen S, Klebe D, Zhang JM, Wu Q. Rapid- developed primary malignant myoepithelioma in the cavernous sinus: A case report. BMC Neurol 2013;13:40.  Back to cited text no. 5
    
6.
Ghanta RK, Uppin MS, Koti K, Hui M, Uppin SG, Mukherjee KK. Primary intracranial Parachordoma: An unusual tumor in brain. Surg Neurol Int 2014;5:S506-11.  Back to cited text no. 6
    
7.
Gupta K, KlimoPJr, Wright KD. A 2-Year-old girl with dysmetria and ataxia. Brain Pathol 2016;26:126-7.  Back to cited text no. 7
    
8.
Chimelli L, Gadelha MR, Une K, Carlos S, Pereira PJ, Santos JL, et al. Intra-sellar salivary gland like pleomorphic adenoma arising within the wall of a Rathke's cleft cyst. Pituitary 2000;3:257-61.  Back to cited text no. 8
    
9.
Antonescu CR, Zhang L, Chang NE, Pawel BR, Travis W, Katabi N, et al. EWSR1-POU5F1 fusion in soft tissue myoepithelial tumors. A molecular analysis of sixty-six cases, including soft tissue, bone, and visceral lesions, showing common involvement of the EWSR1 gene. Genes Chromosomes Cancer 2010;49:1114-24.  Back to cited text no. 9
    
10.
Aström AK, Voz ML, Kas K, Röijer E, Wedell B, Mandahl N, et al. Conserved mechanism of PLAG1 activation in salivary gland tumours with and without chromosome 8q12 abnormalities: Identification of SII as a new fusion partner gene. Cancer Res 1999;59:918-23.  Back to cited text no. 10
    
11.
Kas K, Voz ML, Röijer E, Aström AK, Meyen E, Stenman G, et al. Promoter swapping between the genes for a novel zinc finger protein and beta-catenin in pleiomorphic adenomas with t(3;8)(p21;q12) translocations. Nat Genet 1997;15:170-4.  Back to cited text no. 11
    
12.
Magrini E, Pragliola A, Farnedi A, Betts CM, Cocchi R, Foschini MP. Cytogenetic analysis of myoepithelial cell carcinoma of salivary gland. Virchows Arch 2004;444:82-6.  Back to cited text no. 12
    
13.
Voz ML, Aström AK, Kas K, Mark J, Stenman G, Van de Ven WJ. The recurrent translocation t(5;8)(p13;q12) in pleomorphic adenomas results in upregulation of PLAG1 gene expression under control of the LIFR promoter. Oncogene 1998;16:1409-6.  Back to cited text no. 13
    
14.
Hampton TA, Scheithauer BW, Rojiani AM, Kovacs K, Horvath E, Vogt P. Salivary gland-like tumors of the sellar region. Am J Surg Pathol 1997;21:424-34.  Back to cited text no. 14
    
15.
Nieder C, Schneller F, Grosu AL, Peschel C, Molls M. Radiotherapy and chemotherapy for myoepithelioma of the sellar region. Strahlenther Onkol 2005;181:260-3.  Back to cited text no. 15
    
16.
Curry B, Taylor CW, Fisher AW. Salivary gland heterotopia: A unique cerebellopontine angle tumour. Arch Pathol Lab Med 1982;106:35-8.  Back to cited text no. 16
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]
 
 
    Tables

  [Table 1], [Table 2]



 

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