Simultaneous occurrence of a calcifying odontogenic cyst and its malignant transformation

The authors report a 48-year-old woman with a lesion in the maxilla, where a typical calcifying odontogenic cyst and a malignant tumor occurred simultaneously. She was diagnosed as having a malignant calcifying odontogenic cyst (tumor). The patient died of intracranial extension 20 months after diagnosis. Metastases were not detected.