Central mucoepidermoid carcinoma arising from glandular odontogenic cyst confirmed by analysis of MAML2 rearrangement: A case report

Abstract

Central mucoepidermoid carcinoma (MEC) poses a diagnostic challenge because of its rarity and histological overlap with glandular odontogenic cyst (GOC). In MEC of both salivary glands and jaws, MAML2 arrangement has been well known as the specific gene alteration. We report a case of central MEC arising from GOC diagnosed by MAML2 fusion gene. A 57-year-old male presented a multilocular cystic lesion in left molar region of the mandible. Histopathologically, multiple cysts lined by thin cuboidal or non-keratinized squamous epithelium with small ductlike structures, mucous cells and ciliated cells were present. It was diagnosed as GOC. The recurrent lesion after nine years showed the proliferation of many cystic and solid nests composed of epidermoid, mucous and intermediated cells. Nested PCR revealed CRTC3-MAML2 fusion gene in the recurrent lesion, but not in the primary one. Similarly, MAML-2 rearrangement by FISH analysis was positive in the recurrent lesion, while negative for the primary one, thus confirming the diagnosis of central MEC arising from GOC. Analysis of MAML2 rearrangement can be used as a supportive evidence to distinguish central MEC from 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 arising directly from a glandular odontogenic cyst of the mandible: a case report

“…Central MEC is also very rare, representing only 2 to 4 % of all MECs [ 5 ]. Several cases formerly diagnosed as central MEC may have been cases of GOC and some central MECs could have originated from GOCs [ 4 , 6 ]. There are previously reported cases in which the first biopsy was diagnosed as GOC, but the recurrent lesion was central MEC [ 4 , 6 ].…”

“…Several cases formerly diagnosed as central MEC may have been cases of GOC and some central MECs could have originated from GOCs [ 4 , 6 ]. There are previously reported cases in which the first biopsy was diagnosed as GOC, but the recurrent lesion was central MEC [ 4 , 6 ]. To our knowledge, this is the first case report describing immunohistochemical and MAML-2 rearrangement findings in a case of central MEC occurring directly from GOC.…”