Central mucoepidermoid carcinoma (MEC) is a rare salivary gland tumor that affects the jaw bone. 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.
A 67-year-old Japanese man presented with a cystic lesion in the right third molar region. Histologically, the biopsy specimen demonstrated both typical 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 immunohistochemistry for cytokeratin (CK) profile results demonstrated that while both central MEC and GOC expressed CKs 7, 14, 18, and 19, interestingly CK13 was only expressed in GOC. Fluorescence in-situ hybridization (FISH) revealed the rearrangement of the Mastermind like (MAML)-2 gene in both MEC and GOC components.
Our case suggests that central MEC and GOC may be in the same spectrum of diseases caused by rearrangement of the MAML-2 gene. At the same time, the expression profile of CK13 was completely different in both central MEC and GOC. This also suggests that central MEC is a distinct tumor from GOC. Thus, we demonstrated the rare case that central MEC may have originated directly from the GOC.