Archives of Medicine and Health Sciences

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

Myoepithelioma of lateral pharyngeal wall


Harsh Suri, Vijayalakshmi Subramaniam, Pooja Vasu 
 Department of Otorhinolaryngology, Yenepoya Medical College and Hospital, Deralakatte, Mangalore, Karnataka, India

Correspondence Address:
Dr. Harsh Suri
Department of Otorhinolaryngology, Yenepoya Medical College and Hospital, Deralakatte, Mangalore - 575 018, Karnataka
India

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.



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 Mar 2 ];8:299-301
Available from: https://www.amhsjournal.org/text.asp?2020/8/2/299/304723


Full Text



 Introduction



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



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}{Figure 2}

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}

 Discussion



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



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.

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