Central mucoepidermoid carcinoma arising directly from a glandular odontogenic cyst of the mandible: a case report

Abstract

Background Central mucoepidermoid carcinoma (MEC) is a rare salivary gland tumor that affects the jawbone. Glandular odontogenic cyst (GOC) is also a rare odontogenic developmental cyst with glandular differentiation. GOC shares some histological features with central MEC, and a pre-existing GOC can develop into central MEC. Here, we present a rare case of central MEC developed directly from a pre-existing GOC of the mandible. Case presentation A 67-year-old Japanese man presented with a cystic lesion in the right third molar region. Histologically, the biopsy specimen demonstrated both typical findings of a GOC component lined with non-keratinized squamous epithelium and a recognizable component of central MEC consisting of polycystic nests with mucous cells, intermediate cells, and epidermoid cells in the cyst wall. The results from the immunohistochemistry for cytokeratin (CK) profiling demonstrated that, while both central MEC and GOC expressed CKs 7, 14, 18, and 19, CK13 was interestingly exclusively expressed in GOC. Fluorescence in-situ hybridization (FISH) revealed the rearrangement of the Mastermind like (MAML)-2 gene in both the MEC and GOC components. Conclusions Our case suggests that central MEC and GOC may be in the same spectrum of diseases caused by the rearrangement of the MAML-2 gene. However, given that the expression profile of CK13 was completely different between central MEC and GOC, they can be considered as separate tumors. Overall, we demonstrated a rare case in which central MEC may have originated directly from the GOC.

MAML2-Rearranged Primary Central Mucoepidermoid Carcinoma of the Mandible as an Incidental Finding: A Case Report and Review of the Literature of Molecularly Confirmed Cases

“…MAML2 rearrangement in MEC is not specific to salivary gland origin, as MEC of other origins, such as thymus, lung, lacrimal gland, and uterine cervix, have also demonstrated MAML2 rearrangement [25][26][27][28]. Our literature review only identified nine reports/studies documenting the presence of MAML2 rearrangement in CMEC in 30 cases (Table 1) [10][11][12][13][14][15][16][17][18]. Of these, site and demographic information are provided for 25 cases [10,11,[13][14][15][16][17][18].…”

“…Our literature review only identified nine reports/studies documenting the presence of MAML2 rearrangement in CMEC in 30 cases (Table 1) [10][11][12][13][14][15][16][17][18]. Of these, site and demographic information are provided for 25 cases [10,11,[13][14][15][16][17][18]. The mandible represents 64% of cases, with 36% occurring in the maxilla [10,11,[13][14][15][16][17][18].…”

“…CRTC1/3-MAML2 fusions are specific to MEC and absent in other tumors of salivary gland origin [8,9]. Few reports have documented the presence of MAML2 rearrangement in CMEC [10][11][12][13][14][15][16][17][18].…”

Central mucoepidermoid carcinoma of the mandible deriving from odontogenic cyst: A case report and review of the literature

“…Central MEC is a rare intraosseous variant occurring in the jaws and represents only 2% to 4% of all MECs 10,11 . It occurs most frequently in the fourth and fifth decade of life, with a male to female ratio of 1:1.45 12 ; in 50% of cases, they are associated with odontogenic cyst or unbroken tooth 13 …”

“…10,11 It occurs most frequently in the fourth and fifth decade of life, with a male to female ratio of 1:1.45 12 ; in 50% of cases, they are associated with odontogenic cyst or unbroken tooth. 13 Several theories regarding its origin have been postulated. [14][15][16][17] The most worthy considered neoplastic transformation of the epithelial lining of odontogenic cysts to be the most plausible in tumor's development.…”