Use of molecular diagnostics to distinguish glandular odontogenic cyst and mucoepidermoid carcinoma

Glandular odontogenic cyst (sialo-odontogenic cyst) is an uncommon developmental odontogenic cyst, the clinical significance of which lies in its tendency to recur, and histopathological features which mimic those of mucoepidermoid carcinoma. This report describes three cystic lesions of the jaws with similar histopathological features. One occurred in the mandibular premolar area of a 49-year-old woman and was diagnosed as glandular odontogenic cyst. The second developed in the maxilla of a man aged 39 in association with an impacted second premolar tooth. This was initially diagnosed as dentigerous cyst, but after recurrence six years later the diagnosis was revised to glandular odontogenic cyst. The third occurred in a 30-year-old woman five years after the extraction of a mandibular third molar in the same site as the lesion; a diagnosis of glandular odontogenic cyst was initially favoured, but a third biopsy (taken over a year later) showed unequivocal, invasive mucoepidermoid carcinoma which had infiltrated nerves and bone. Glandular odontogenic cyst and mucoepidermoid carcinoma may be inseparable on the basis of histopathological features, but the presence of a rearrangement of the MAML2 gene, as detected by FISH, distinguishes the two and offers the potential for prompt diagnosis and appropriate treatment.