|Year : 2020 | Volume
| Issue : 4 | Page : 414-416
Innocuous presentation of low-grade mucoepidermoid carcinoma of the palate
Thilak T John1, Manisha M Khorate1, Nivedita Chinam1, Poonam R Sawant2
1 Department of Oral Medicine and Radiology, Goa Dental College and Hospital, Bambolim, Goa, India
2 Department of Oral and Maxillofacial Pathology, Goa Dental College and Hospital, Bambolim, Goa, India
|Date of Submission||27-Aug-2020|
|Date of Decision||18-Nov-2020|
|Date of Acceptance||25-Nov-2020|
|Date of Web Publication||28-Dec-2020|
Dr. Thilak T John
E-101 Sumit Province HSG Ltd., Near TVS Showroom, Dhavali, Ponda - 403 401, Goa
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Mucoepidermoid carcinoma (MEC) is a malignant epithelial tumor and is the most common minor salivary gland neoplasm. The initial presentation of this pathology can resemble benign lesions and can be misleading. They often present as asymptomatic swellings along minor salivary gland bearing areas. Proper attention to clinical features and the use of advanced imaging is of paramount importance to detect these innocuous lesions. We report an incidental finding of a palatal swelling in a 27-year-old female. This paper reports a low-grade MEC with unremarkable clinical features showing underlying bone involvement. It highlights the need for decisive investigations and accurate diagnosis in cases of malignant tumors of the minor salivary glands as it can reduce morbidity and prevent mortality.
Keywords: Immunohistochemistry, minor salivary gland, mucoepidermoid carcinoma, neoplasm, palate
|How to cite this article:|
John TT, Khorate MM, Chinam N, Sawant PR. Innocuous presentation of low-grade mucoepidermoid carcinoma of the palate. J Indian Acad Oral Med Radiol 2020;32:414-6
|How to cite this URL:|
John TT, Khorate MM, Chinam N, Sawant PR. Innocuous presentation of low-grade mucoepidermoid carcinoma of the palate. J Indian Acad Oral Med Radiol [serial online] 2020 [cited 2021 Jan 27];32:414-6. Available from: https://www.jiaomr.in/text.asp?2020/32/4/414/305272
| Introduction|| |
Mucoepidermoid carcinoma (MEC) is a malignant epithelial tumor that was first reported by Massao and Berger in 1942 and identified as a separate entity by Stewart et al. in 1945. It is said to originate from pluripotent cells of the excretory duct comprising of varying proportions of salivary gland cells. The etiology of MEC is unclear but may be attributed to the translocation of gene t(11;19) (q21;p13.1) while some authors believe exposure to ionizing radiation to be a contributing factor. MEC most commonly involves the parotid gland, followed by the submandibular gland. When this tumour involves the minor salivary glands, it is the palatal region that is the most common site. In this report, we discuss a case of low-grade MEC in a 27-year-old female patient with clinical, imaging, and immunohistochemical back-up.
A 27-year-old female with no medical history reported for an annual dental check-up. On oral examination, swelling along the left posterior hard palate was noted. It was well defined, dome-shaped with a bluish hue, measuring approximately 1.2 × 0.6 × 0.2 cm along the left posterior hard palate, 1.2 cm away from the marginal gingiva of maxillary right first molar and with hyperaemic surrounding mucosa [Figure 1]. On palpation, the swelling was non-tender, soft, compressible, fluctuant with a smooth contour and fixed to the underlying bone. The adjacent teeth did not elicit any abnormality. The cervical lymph node examination did not reveal any palpable node. Thermal pulp vitality test results carried out on the maxillary left premolars and molars showed a normal response. Intraoral periapical radiograph of the right maxillary molars revealed no pulpal, periapical, and periodontal changes. Considering the soft nature of the swelling with a blue hue, not associated with teeth and supporting structures, and no lymph node enlargement, a provisional diagnosis of mucocele was made. We considered minor salivary gland neoplasm of which MEC as a differential diagnosis owing to its soft consistency, blue hue and frequency in the palate.
|Figure 1: Intraoral photograph showing a well-defined dome shaped swelling with a smooth surface and a bluish hue|
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Since palatal vault cannot be adequately visualized on conventional radiographs, a Contrast-Enhanced Computed Tomography (CECT) scan was taken to assess the underlying palatal bone status. A relatively well-defined hypodense lesion over the posterior hard palate in the region of the first molar measuring1.2 × 1 × 0.6 cm was noted. Erosion of the underlying palatal bone was noted. Post-contrast, the lesion showed homogenous enhancement [Figure 2]. These findings suggested malignant neoplasm. There was no involvement of the maxillary sinus and the scan was negative for lymph node involvement.
|Figure 2: (a) Coronal section of CT showing palatal lesion with erosion of underlying bone. (b) Coronal section CECT showing enhancement of the palatal lesion|
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Incisional biopsy report revealed a polypoid lesion composed of dilated ducts lined by clear to intermediate cells and few mucin filled cells and squamous cells with luminal secretions [Figure 3]. This suggested MEC. Thereafter, immunohistochemistry was performed to determine the grade of the malignancy. Markers like CK (AE1/AE3), Vimentin (V9), S100, P63, and CK5/6 were positive, all of which suggests low-grade variant of MEC [Figure 3].
|Figure 3: Photomicrographs of the haematoxylin and eosin stained section of mucoepidermoid carcinoma (a) and the immunohistochemical marker panel showing positive expression of P63(b), AE1/AE3(c) and S-100 (d)|
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The patient was treated promptly with a wide local excision, followed by a palatal obturator to rehabilitate the surgical defect. Radiotherapy or chemotherapy was not considered as it was a low-grade variant of MEC.
Follow-up and outcomes
The patient is under regular follow-up for the past 2 years following the treatment and no recurrence had been observed till date [Figure 4].
|Figure 4: Post-operative intraoral photograph showing a surgical defect with clear margins|
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| Discussion|| |
MEC is a well-recognized malignancy known to involve minor salivary glands in various areas in the oral cavity. MEC of the hard palate is usually asymptomatic, goes unnoticed and untreated. A compressible palatal mass in adolescents should prompt a differential diagnosis of reactive and neoplastic lesions. A palatal mass with a blue hue in a salivary gland bearing area indicates MEC or a mucocele.
The prognosis and recurrence rates of MEC show a strong correlation to its pathological variants. It is commonly divided into low, intermediate, or high-grade tumors based on the differentiation of cells. Mucus producing cells and poorly differentiated epidermoid cells are predominant in high grade tumors, whereas intermediate tumors make up a mix of both cell types. Low-grade tumors have a low recurrence rate and almost 100% survival. Intermediate and high grades have a recurrence rate of around 30% and 70%, respectively. Survival similarly decreases to 70% and 40% for intermediate and high grades, respectively. Spiro RH et al. reported a cure rate of 92%, 63%, and 27% in low, intermediate, and high-grade tumors, respectively.
The prognosis of MEC should be predicted based on histological grade, clinical stage, surgical margins, perineural and vascular involvement, and lymph node metastasis. Xu W et al. stated that “a combination of CD44, CD133, and SOX2 was a powerful and practicable prognostic indicator for patients with MEC of the palate.” Low and intermediate-grade tumors have an excellent prognosis, whereas high-grade tumors exhibit significantly lower prognosis owing to its aggressive nature and higher recurrence rate. Features like bone resorption, root resorption, and bone infiltration are characteristic of the advanced lesion. Pain or ulceration present in the advanced stages of the disease prompts the patient to seek medical assistance. In the present case, the tumor was detected at an earlier stage aiding us to an early diagnosis and management.
Conventional radiography can often be misleading the early presentation of a case of a minor salivary gland tumor as findings like the erosion of adjacent bone may not be appreciated. Hence one must rely on advanced imaging techniques for differentiation of benign and malignant lesions. In the present case, the findings of CECT played a key role in arriving at a clinic-radiographic opinion of a malignant neoplasm.
Earlier studies on CT findings of 63 histopathologically proven minor salivary gland tumors of the palate noted findings like aggressive bone destruction, tumor extension into the pterygopalatine fossa, and calcifications within a tumor can aid in an accurate differentiation of benign and malignant lesions. However, CT finding alone may not establish an accurate diagnosis in cases without bone erosion. MRI findings of palatal tumors of low-grade tumors have smooth margins and appear as hyperintense spots on T1- and T2-weighted images because of mucin-containing cystic components. In contrast, high-grade tumors appear solid with poorly defined margins, often present as hypo or isointense lesions on T2-weighted images, showing their high cellularity.
Treatment of MEC depends on factors like histological grade, lymph node involvement, and its extent. A low-grade tumor may be managed more conservatively with surgical excision with clear margins. In contrast, high-grade tumors involving adjacent structures or lymph nodes can warrant more aggressive surgical procedures and neck dissections.
Though the patient doesn't experience any discomfort, she understood the nature of the disease condition and cooperated well. She didn't experience any posttreatment complications.
| Conclusion|| |
This case emphasizes every examiner be vigilant while evaluating palatal swellings. Once the inflammatory and odontogenic causes are ruled out, minor salivary gland tumors are the next common entities presenting in the palate. The advanced imaging techniques play a major role in aiding to differentiate between benign and malignant salivary gland tumors. An early diagnosis can improve the prognosis and reduce the morbidity of the patient.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has given her consent for her 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.
We would like to acknowledge the contribution of the Departments of Oral and Maxillofacial Surgery and Oral and Maxillofacial Pathology, Goa Dental College and Hospital, Bambolim, Goa.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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