|Year : 2022 | Volume
| Issue : 4 | Page : 183-186
Myoepithelial carcinoma of mandible: A rare case with literature review
Rituparna Biswas1, Anirban Halder1, Mimi Gangopadhyay2, Tshering Doma Bhutia3, Dipanwita Biswas4
1 Department of Radiation Oncology, Medica Cancer Hospital, Siliguri, West Bengal, India
2 Department of Pathology, North Bengal Medical College, Siliguri, West Bengal, India
3 Department of Surgical Oncology, Medica Cancer Hospital, Siliguri, West Bengal, India
4 Department of Psychiatry, R G Kar Medical College, Kolkata, West Bengal, India
|Date of Submission||27-Feb-2021|
|Date of Acceptance||14-Jun-2021|
|Date of Web Publication||12-Aug-2021|
Dr. Anirban Halder
Department of Radiation Oncology, Medica Cancer Hospital, Rangapani, Siliguri, West Bengal
Source of Support: None, Conflict of Interest: None
Primary salivary gland carcinomas of intraosseous origin of the mandible are uncommon neoplasms. Myoepithelial carcinoma (MC) happens to be the rarest. Detailed descriptions of its clinical course are hence not available. Herein, we report a case of MC affecting the mandibular central arch in a bizarre way in a 15-year-old adolescent girl who was treated effectively with definitive radiotherapy (RT) along with concurrent chemotherapy in view of unresectability. To the author's best knowledge, this is the fifth reported case of MC affecting the mandible and the first case to be treated by radical RT. Our study sheds light on the fact that RT can be an effective alternative to surgery where it is not feasible.
Keywords: Salivary gland neoplasms, myoepithelial carcinoma, mandible
|How to cite this article:|
Biswas R, Halder A, Gangopadhyay M, Bhutia TD, Biswas D. Myoepithelial carcinoma of mandible: A rare case with literature review. J Med Sci 2022;42:183-6
|How to cite this URL:|
Biswas R, Halder A, Gangopadhyay M, Bhutia TD, Biswas D. Myoepithelial carcinoma of mandible: A rare case with literature review. J Med Sci [serial online] 2022 [cited 2023 May 31];42:183-6. Available from: https://www.jmedscindmc.com/text.asp?2022/42/4/183/353050
| Introduction|| |
Primary salivary gland carcinomas of intraosseous origin from the mandible are rare neoplasms. As defined by the WHO, myoepithelial carcinoma (MC) is considered as a neoplasm with myoepithelial differentiation marked by local infiltration and ability for distant metastasis. MC accounts for fewer than 2% of the salivary gland neoplasms as noted in series. The most commonly involved sites of MC are parotid gland, followed by minor salivary glands of palate, nasopharynx, paranasal sinus, and nasal cavity in the head-and-neck region., Extra salivary intraosseous MC of the mandible is exceedingly rare. We experienced a case of MC affecting the midline arch of the mandible in a bizarre way in a 15-year-old adolescent girl who was treated effectively with definitive radiotherapy (RT) along with concurrent chemotherapy in view of unresectability. Extensive literature survey reveals it to be the fifth reported case and the first case to be treated by radical RT.
| Case Report|| |
An otherwise well, 15-year-old adolescent presented with huge and bizarre growth over the lower jaw for 1 year. There was no significant past, familial, or birth history. Examination revealed a large proliferative growth which widened the oral aperture and was projecting outside; no cervical lymph nodes were palpable [Figure 1]a. Contrast-enhanced computed tomography (CECT) and contrast-enhanced magnetic resonance imaging (CEMRI) showed a 157 mm × 109 mm × 92 mm sized lytic expansile mass arising from the body of the mandible anteriorly on both sides with matrix mineralization, periosteal reaction, and extensive soft-tissue component. The mass completely filled the oral cavity and posteriorly compressed the tongue with loss of intervening fat plane, and there was narrowing of oropharyngeal air column. The mass is superiorly abutting hard palate and inferiorly bulged into floor of the mouth. Multiple floating teeth and dislocated right temporomandibular joint were also noted. On CEMRI, the mass showed a T1 isointense signal with internal T1 hypo- and hyperintense signal and T2 and short inversion time inversion recovery iso-to-hyperintense signal with moderate heterogeneous postcontrast enhancement with internal nonenhancing foci. Few small bilateral level IB and II lymph nodes were also seen (largest measured 13.5 mm × 7.3 mm) [Figure 2]. Biopsy from tumor was done, and subsequent immunohistochemistry (IHC) suggested it to be a MC. Tumor cells were strongly positive for cytokeratin (CK),epithelial membrane antigen (EMA), vimentin, CD99; patchy moderately positive for smooth muscle actin (SMA), S-100, weakly positive for Fli-1, SATB-2, synaptophysin, CD56; and negative for desmin, myogenin, p63, TLE-1, CD34, calponin, WT-1, PAX-8. Ki-67 was 30% [Figure 3]. CECT thorax and abdomen were done to exclude distant metastases which showed nothing contributory. In view of extensive disease which would require massive reconstruction, tumor was deemed unresectable at the outset. She was then treated with definitive RT with dose 70 Gray in conventional fractionation over 7 weeks concurrent with weekly cisplatin (40 mg/m2). For simulation and treatment, she was immobilized with thermoplastic mold in supine position with head extended using head rest. CT simulation using 3-mm thickness with intravenous contrast was performed. For target volume delineation, all visible tumors in CECT scan including primary and nodal disease (level 1B and II) were taken into account as gross tumor volume70; bilateral level III–V neck levels were included in high-risk clinical target volume (CTV60). Finally, a 5-mm margin to CTV was given to produce planning target volume. Wet cotton bolus was used during treatment. Radiation planning was done by forward planning intensity-modulated radiation therapy. She was assessed weekly to assess tolerance and response. After 3 weekly cycles of cisplatin, further chemotherapy had to be withheld due to progressive elevation of liver enzymes (serum glutamic-oxaloacetic transaminase and serum glutamic-pyruvic transaminase), which came back to normal in few weeks upon discontinuation.
|Figure 1: (a) Clinical picture at baseline; (b and c) Clinical picture at 6 months postradiotherapy completion (arrow showing small residual tumor at the floor of the mouth)|
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|Figure 2: (a and b) Contrast-enhanced computed tomography scan showing neoplasm in axial and sagittal view, respectively; (c) Contrast-enhanced magnetic resonance imaging showing tumor in coronal view|
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|Figure 3: (a) Myoepithelial carcinoma as seen on H and E staining. Immunohistochemistry positivity seen for (b) S-100, (c) CD99, (d) cytokeratin, (e) epithelial membrane antigen, and (f) Smooth muscle actin|
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She was reviewed after 2 months of RT completion when it was found that tumor has reduced substantially clinicoradiologically [Figure 4]. CEMRI of the face and neck revealed a residual tumor of 84 mm × 49 mm × 42 mm arising from the body of the mandible. Hence, she was offered surgery to which she refused due to financial constraints. She was reviewed again at 6 months post-RT completion, when only a small residual tumor was observed at the floor of the mouth [Figure 1]b and [Figure 1]c signifying continued tumoricidal action of RT. She did not receive any tumoricidal treatment during this follow-up period. She was lost to follow-up for further surveillance.
|Figure 4: (a) Clinical picture at 2 months postradiotherapy completion; (b and c) Contrast-enhanced magnetic resonance imaging showing residual tumor in axial and sagittal view, respectively|
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| Discussion|| |
Heterotopic salivary gland tissue had been found in various tissues such as lymph nodes, middle ear, parathyroid, thyroid, breast, pituitary, lung, skin, maxilla, and mandible. Its neoplastic conversion is unusual. Salivary gland carcinomas originating from the central arch of the mandible are rare, accounting for fewer than 0.4% of all salivary gland malignancies. Mucoepidermoid carcinoma is the most common histologic variant found. MC of the mandible is an extremely rare clinical case. Exhaustive literature review reveals that index patient is the fifth reported case as per existing evidences [Table 1]. Myoepithelioma is the benign counterpart. Local tissue infiltration is the hallmark histological feature that differentiates malignant from benign myoepithelioma along with other features such as nuclear atypia and high mitotic count., Clinically and radiologically, MC of the mandible mimics other odontogenic tumors and exact diagnosis can only be made on histologic examination. In our presented case, swelling or mass in the lower jaw was extraordinarily large, filling entire oral cavity, protruded out of oral aperture even threatening posterior airway column of obstruction. Such clinical picture had never been described in previously reported cases.,,, Clinically, it was not even possible to understand the site of origin of tumor. Only after radiological investigations (CECT and CEMRI), it was known that neoplasm was arising from the anterior arch of the mandible with widespread local extensions. In previously described cases, swellings were relatively small and were found in the lateral aspect of the mandible (body/ramus), mainly over the right side [Table 1]. The histology of central salivary gland neoplasms in the mandible including MC is identical to that of their salivary gland counterparts and usually does not pose diagnostic difficulties. IHC reveals marked positivity for epithelial markers such as CK, EMA, S-100 protein, and smooth muscle markers, for example, SMA and calponin. The present IHC criteria for the diagnosis of myoepithelial differentiation are dual positivity for both CK and ≥1 myoepithelial marker (i.e., S-100, p63, actins, maspin, GFAP, and calponin). IHC revelations in index case are consistent with previously published literature. Surgical excision is the primary treatment modality for managing primary salivary gland neoplasms of the mandible including MC. Yu proposed that MC of the salivary gland should be regarded as high-grade malignancies as recurrence and metastases are often seen even after excision with negative surgical margins. Hence, postoperative adjuvant RT along with chemotherapy had been suggested., Although never had been RT used for treating MC of the mandible in primary setting as per existing literature, in our case, we hardly had any choice as surgery was not feasible due to extensive disease and her life was at stake. To our surprise, she responded immensely well to RT and hence she lives to tell a tale.
|Table 1: Clinical and treatment characteristics of four patients with myoepithelial carcinoma of the mandible as found in existing English literature|
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| Conclusion|| |
We present an exceedingly rare case of MC of the mandible who was treated effectively with RT and concurrent chemotherapy. Our evidence gives hope that RT is an effective alternative to surgery where it is not feasible.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient's father has given his consent for images and other clinical information to be reported in the journal. The patient's father understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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