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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 8  |  Issue : 2  |  Page : 299-301

Myoepithelioma of lateral pharyngeal wall


Department of Otorhinolaryngology, Yenepoya Medical College and Hospital, Deralakatte, Mangalore, Karnataka, India

Date of Submission24-Oct-2020
Date of Decision13-Dec-2020
Date of Acceptance14-Dec-2020
Date of Web Publication23-Dec-2020

Correspondence Address:
Dr. Harsh Suri
Department of Otorhinolaryngology, Yenepoya Medical College and Hospital, Deralakatte, Mangalore - 575 018, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/amhs.amhs_284_20

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  Abstract 


Myoepithelioma is an extremely rare subtype of salivary gland tumors, and its diagnosis is made on a wide variation of cellular morphology. Though benign, it has a tendency for local metastasis and has a low recurrence rate. Its diagnosis can be challenging due to its poorly characterized clinical, histological, and immunochemical behavior. Here, we present a rare presentation of this tumor in the lateral pharyngeal wall.

Keywords: Benign tumors, myoepithelioma, Lateral pharyngeal wall


How to cite this article:
Suri H, Subramaniam V, Vasu P. Myoepithelioma of lateral pharyngeal wall. Arch Med Health Sci 2020;8:299-301

How to cite this URL:
Suri H, Subramaniam V, Vasu P. Myoepithelioma of lateral pharyngeal wall. Arch Med Health Sci [serial online] 2020 [cited 2021 Jan 18];8:299-301. Available from: https://www.amhsjournal.org/text.asp?2020/8/2/299/304723




  Introduction Top


Myoepithelioma is a benign tumor composed of myoepithelial cells. They constitute a major portion of various salivary gland tumors but are found in many other sites, such as nasopharynx, breast, larynx, sweat glands, and skin.[1] Being one of the rarest tumors, they account for less than 1.5% of all salivary gland tumors.[2] They are commonly seen in the fourth decade of life and are usually benign and present as an asymptomatic mass which grows slowly over a period of months to years.[3] About 50% of salivary gland myoepitheliomas arise in the parotid gland. The sublingual salivary glands account for 33%, submandibular glands for about 13%, and minor salivary glands for 2%–4%.[4] They are also known to occur in the oral cavity and constitute less than 1% of salivary gland myoepitheliomas, with palate being the most common site of occurrence.[5],[6]

Here, we present a rare case of myoepithelioma arising from the lateral pharyngeal wall.


  Case Report Top


A 33-year-old woman who was nonalcoholic, nonsmoker presented to the ear-nose-throat outpatient department with a history of a mass hanging behind the uvula, which was slowly progressive in size for the past 4 months with no history of any other comorbidities. There was no history suggestive of dysphagia, odynophagia, voice change, weight or appetite loss, snoring, or fever. The clinical examination revealed a globular reddish mass seen hanging behind the uvula, which was firm, nontender, and nonpulsatile, with no ulceration or erosion of the overlying mucosa. There were no palpable lymph nodes in the neck. Routine diagnostic rigid nasal endoscopy revealed a mass arising from the lateral pharyngeal wall below the level of choana.

Contrast-enhanced magnetic resonance imaging was performed to further characterize the lesion, which revealed a homogeneously enhancing thin-walled mass arising from the left oropharyngeal wall approximately measuring 1.3 cm × 1 cm × 1.4 cm, suggestive of a benign mass [Figure 1] and [Figure 2].
Figure 1: Sagittal view of contrast enhanced magnetic resonance imaging showing the thin walled cyst arising from the lateral pharyngeal wall

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Figure 2: Axial view of contrast enhanced magnetic resonance imaging showing the thin walled cyst arising from the lateral pharyngeal wall

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Based on the clinicoradiological features, a diagnosis of benign lateral pharyngeal mass was made. The patient underwent a wide local excision of the tumor via transoral approach under general anesthesia. Specimen was sent for histopathological analysis, which revealed stratified squamous epithelium with an underlying well-circumscribed neoplasm. The neoplasm was composed of sheets of polygonal cells, with eccentric nuclei and a moderate amount of cytoplasm. The cells were fairly uniform with vesicular nuclei having small prominent nucleoli. In areas, cells had granular and vacuolated cytoplasm suggestive of myoepithelioma [Figure 3]. The tumor was positive for vimentin, smooth muscle antigen, and S-100 on immunohistological staining. These findings were confirmatory of myoepithelial tumor.
Figure 3: Histopathological photograph showing features suggestive of myoepithelioma (H and E stain, ×20)

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  Discussion Top


Myoepitheliomas are essentially benign tumors of salivary glands. Although they were considered to be a variant of pleomorphic adenoma, they have been categorized as a separate entity by the World Health Organization since 1991.[7] These are rare head-and-neck tumors which can be defined clinically or found incidentally on radiology. Due to the inherent variation of cellular morphological patterns, diagnosis relies heavily on histology and immunohistochemistry of the lesion.[8]

Majority of the myoepithelial cells are found in major and minor salivary glands. They are also found in many extrasalivary structures, such as sweat glands, lacrimal glands, prostrate, breast, nasopharynx, lungs, retroperitoneal area, and skin.[9] Four different morphological patterns of myoepitheliomas are known which include nonmyxoid (solid), myxoid (resembling pleomorphic adenoma), reticular pattern, and mixed type.[10]

Pleomorphic adenoma is considered as the most common minor salivary gland tumor constituting about 40% of total cases. Presence of chondromyxoid matrix is considered as the characteristic feature for pleomorphic adenoma which is absent in myoepithelioma.[11]

Benign myoepitheliomas have a low recurrence rate but should always be differentiated from its malignant counterpart, which are more aggressive and show recurrence even after complete treatment. Presence of cellular atypia, necrosis, increased mitotic figures, and invasive growth patterns histologically may favor the diagnosis of malignant myoepithelioma.[11],[12] Vimentin and S-100 proteins are usually found in normal myoepithelial cells and are very sensitive, nonspecific markers of neoplastic myoepithelium.[12]

Other differential diagnosis includes soft tissue tumors such as leiomyoma, which is S-100 protein negative. Although schwannomas are positive, they display characteristic histological features.[13]

Immunohistochemistry is therefore important in making a diagnosis to differentiate it from other tumors. Complete surgical excision is the treatment of choice for benign myoepitheliomas. Transoral tumor excision was done in this case, and this patient had no recurrence on 1 year of follow-up.

The prognosis for benign myoepithelioma, however, remains good provided surgical excision is complete.


  Conclusion Top


Myoepitheliomas are benign tumors most commonly presenting as asymptomatic slowly growing masses, occurring more commonly in the major salivary glands and less than 1% in other sites.

Our case highlights the rare location of the tumor, i.e., lateral pharyngeal wall, and the diagnostic challenge in identifying and managing these conditions.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Ferri E, Pavon I, Armato E, Cavaleri S, Capuzzo P, Ianniello F, et al. Myoepithelioma of a minor salivary gland of the cheek: Case report. Acta Otorhinolaryngol Ital 2006;26:43-6.  Back to cited text no. 1
    
2.
Sciubba JJ, Brannon RB. Myoepithelioma of salivary glands: Report of 23 cases. Cancer 1982;49:562-72.  Back to cited text no. 2
    
3.
Barnes L, Appel BN, Perez H, El-Attar AM. Myoepithelioma of the head and neck: Case report and review. J Surg Oncol 1985;28:21-8.  Back to cited text no. 3
    
4.
Yadav AK, Nadarajah J, Chandrashekhara SH, Tambade VD, Acharya S. Myoepithelioma of the soft palate: A case report. Case Rep Otolaryngol 2013;2013:642806.  Back to cited text no. 4
    
5.
Hiwatashi A, Matsumoto S, Kamoi I, Yamashita H, Nakashima A. Imaging features of myoepithelioma arising from the hard palate. A case report. Acta Radiol 2000;41:417-9.  Back to cited text no. 5
    
6.
Onbas O, Karasen RM, Gursan N, Kantarci M, Alper F, Okur A, et al. Giant myoepithelioma of the face: MDCT with 2D and 3D images. AJR Am J Roentgenol 2006;187:W418-9.  Back to cited text no. 6
    
7.
Sheldon WH. So called mixed tumours of salivary glands. Arch Pathol 1943;35:1-20  Back to cited text no. 7
    
8.
Anmolsingh R, Yu B, Mirza O, Rocke J, Ranganathan B, et al. (2017) Myoepithelioma of the Posterior Oropharyngeal Wall: A Difficult Diagnosis. J Surg Open Access 3(2): doi http:// dx.doi.org/10.16966/2470-0991.141.  Back to cited text no. 8
    
9.
Nair BJ, Vivek V, Sivakumar TT, Joseph AP, Varun BR, Mony V, et al. Clear cell myoepithelioma of palate with emphasis on clinical and histological differential diagnosis. Clin Pract 2014;4:628.  Back to cited text no. 9
    
10.
Dardick I. Myoepithelioma: Definitions and diagnostic criteria. Ultrastruct Pathol 1995;19:335-45.  Back to cited text no. 10
    
11.
Ren J, Liu Z, Liu X, Li Y, Zhang X, Li Z, et al. Primary myoepithelial carcinoma of palate. World J Surg Oncol 2011;9:104.  Back to cited text no. 11
    
12.
Alos L, Cardesa A, Bombi JA, Mallofre C, Trasera J. Myoepithelial tumours of salivary glands: A clinico-pathologic, immunohistochemical, ultrastructural and glow cytometric study. Semin Diagn Pathol 1996;13:138-47.  Back to cited text no. 12
    
13.
Merino MJ, LiVolsi VA. Pleomorphic adenomas of the parotid gland resembling mesenchymal tumors. Oral Surg Oral Med Oral Pathol 1977;44:405-10.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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