|Year : 2014 | Volume
| Issue : 1 | Page : 64-66
Mucoepidermoid carcinoma of the anterior maxilla: A rare entity
Smitha Kullaje1, Vishnudas Prabhu1, Sarah Thomas2, Prashanth Yethadka Keshava3
1 Department of Oral Pathology, Yenepoya Dental College, Mangalore, Karnataka, Kerala, India
2 Department of Oral Pathology, Century International Institute of Dental Science and Research Centre, Kasaragod, Kerala, India
3 Department of Oral and Maxillofacial Surgery, Century International Institute of Dental Science and Research Centre, Kasaragod, Kerala, India
|Date of Web Publication||4-Jun-2014|
Department of Oral Pathology, Yenepoya Dental College, Yenepoya Unievrsity, Deralakatte, Mangalore - 575 018, Karnataka
Source of Support: None, Conflict of Interest: None
Mucoepidermoid carcinoma is the second most common salivary gland tumor primarily involving major salivary glands and intraoral minor salivary glands. Although rare, it can occur in the jaw bones, but it is very rare in the maxillary anterior region. Here, we present a case of mucoepidermoid carcinoma occurring in maxillary anterior region in a 33-year-old male patient presented as painless swelling clinically appearing similar to a periapical or nasopalatine cyst. The final diagnosis of this lesion was made after microscopic examination of biopsy specimen.
Keywords: Anterior maxilla, mucoepidermoid carcinoma, salivary gland tumor
|How to cite this article:|
Kullaje S, Prabhu V, Thomas S, Keshava PY. Mucoepidermoid carcinoma of the anterior maxilla: A rare entity. Arch Med Health Sci 2014;2:64-6
| Introduction|| |
Mucoepidermoid carcinoma is the most common malignant neoplasm of major and minor salivary glands.  The first description of mucoepidermoid carcinoma (MEC) was given by Stewart et al. in 1945, who described it as a separate entity among salivary neoplasm. MEC is thought to arise from pluripotent reserve cells of the excretory ducts of salivary gland that have the potential to differentiate into squamous, columnar, mucous cells, clear cells, and epidermoid cells. Although no specific etiologic factors have been identified, exposure to ionizing radiation has been reported in some cases. 
MEC is known to be composed of a mixture of cells, which includes mucous cells, epidermoid, and intermediate types. MEC shows different levels of aggressiveness correlating with its histologic features and are graded in three stages. 
MEC is a tumor commonly seen in parotid gland in pediatric age group. However, there are very few reports, describing the occurrence of this entity in labial side of maxillary anterior region.  MEC arising in this region poses a diagnostic challenge as salivary glands are not a normal finding in this region.  We report an unique case of MEC in an adult; accurate diagnosis was possible only because of histopathological examination. This indicates the significance of subjecting the lesional tissue for microscopic examination.
| Case Report|| |
A 33-year-old male patient reported to a private dental clinic with complaint of a swelling in the upper front region of the jaw since 3 months. The swelling slowly increased to attain the present size. There was no associated symptom and no history of trauma. Past medical and dental history were non-contributory.
Extraoral examination revealed a diffused swelling in maxillary anterior region. The skin over the swelling was normal with no rise in temperature and non-tender on palpation. Intraoral examination revealed a roughly oval swelling on the upper labial mucosa, which was 3 × 3 cms in size extending from right maxillary central incisor to left maxillary central incisor region extending to involve the attached and the marginal gingiva [Figure 1]. The swelling was uniformly firm and non-tender. The overlying mucosa appeared stretched. There was mobility of the adjacent teeth. Intraoral periapical radiograph showed a well-defined, unilocular radiolucent lesion with thick sclerotic borders. Extension of the lesion was from right maxillary central incisor to left maxillary central incisor region. Radiographic examination revealed bone resorption in relation to 11 and 21. Based on clinical examination, a provisional diagnosis of periapical pathology was made.
FNAC was performed, which was suggestive of a benign salivary gland neoplasm. Accordingly, excision of the lesion was done and the specimen was sent for histopathological examination. On microscopic examination of sections stained with Hematoxylin and Eosin, many mucous cells exhibiting clear cytoplasm along with mucin pooled areas of varying sizes distributed in a connective tissue stroma were seen. Many uniform intermediate cells having a large nucleus with minimal cytoplasm arranged in sheets in between the mucous cells were also observed. Some areas were suggestive of the presence of epidermoid cells. In some areas, tumor cells were found to be invading the bone. Correlating with clinical history, the histopathological features were suggestive of low-grade mucoepidermoid carcinoma. This was confirmed with Periodic Acid Schiff and Mucicarmine stain.
| Discussion|| |
Mucoepidermoid carcinoma is the most common malignant salivary gland tumor, accounting for about 2.8%-15% of all salivary gland tumors.  Most commonly affected major salivary gland is parotid gland, and the most common intraoral site is the posterior palate.
Our case is of mucoepidermoid carcinoma of the anterior maxillary region and is in a rare site of occurrence since salivary glands are absent in this site. The development of mucoepidermoid carcinoma in this region could be due to the occurrence of ectopic salivary glands.  Mucoepidermoid carcinoma has a predilection for adults in their second to eighth decades of life, with slight female predilection. 
Intraorally, low-grade MECs tends to be of long duration and asymptomatic. In the present case, the patient was asymptomatic for a duration of 3 months. As the lesion was asymptomatic, the patient failed to recognize the lesion, and there are possibilities of a much earlier occurrence of the tumor mass.
Several histological variants has been reported, including sclerosing, intraosseous, clear cell, goblet cell, spindle cell types.  The histologic grade of the MEC is proved to often show parallelism with the clinical manifestations of the tumor.
Mucoepidermoid carcinoma is classified based on the degree of cyst formation, proportion of cell types, and the presence or absence of cytomorphologic atypia as low-(15%-62% of patients), intermediate-(9%-48%), or high-grade (22%-38%) malignancy.
- Low-grade: It is a highly differentiated neoplasm with a predominance of macro- and microcysts. Presence of intermediate and mucin-producing cells with minimal cellular atypia is seen
- Intermediate grade: This shows predominance of intermediate cells and a few cysts. Presence of mucin-producing cells and islands of epidermoid cells are seen.
- High-grade: It is a poorly differentiated neoplasm with predominance of intermediate and epidermoid cells in solid blocks. Mucin-producing cells are present with nuclear pleomorphism and mitotic activity. 
In our case, the histopathological findings showed the predominance of mucous cells followed by intermediate cells with many varying-sized cystic spaces containing mucin pooled areas and no cytologic atypia. Thus, a diagnosis of low-grade mucoepidermoid carcinoma was made.
Considering the clinical stage and histological grade as the main prognostic factors, the low-grade carcinoma without metastasis said to have a good prognosis.  Distant metastasis is rare in case of minor salivary glands although cervical lymph node metastasis has been reported.
In a previous study of mucoepidermoid carcinoma, a local recurrence of 12.7% in a mean interval of 41.7 months was seen. The regional metastasis was 9.8% in 173 patients. They also mentioned a 92% to 100% survival rate for low-grade, 62% to 92% for intermediate grade, and 0% to 43% for high-grade. According to Ellis et al., there is an overall recurrence of 25% with a 10% recurrence for low-grade and 75% recurrence for high-grade mucoepidermoid carcinoma. These reports confirm the good prognosis of low-grade carcinoma as reported in our case.
| Conclusion|| |
MEC in the anterior maxillary region is a rare entity. However, occurrence in the anterior maxillary region cannot be overlooked because MEC often masquerades as a benign or inflammatory condition. Use of histopathological examination can greatly help in the diagnosis as well as identifying the involvement of the adjacent vital structures, which may change the treatment and the prognosis. MEC should be followed-up for a longer duration to detect late local recurrence and regional metastasis.
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