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A calcifying epithelial odontogenic tumor, simultaneously located in the two jaws (maxilla and mandible) was examined by histochemical and electron microscopic methods. Squamous tumor cells without secretory polarity were different from those of common ameloblastoma. High activities of alkaline phosphatase and ATPases were demonstrated by light and electron microscopy on the cytoplasmic membrane, findings similar to those in the stratum intermedium cells of the normal dental germ from which these tumor cells seem to arise. The tumor cells, like preameloblasts of the dental germ, also produce a granulo-filamentous material in intracytoplasmic vesicles and discharge it into the stroma. This "pseudo-amyloid" substance represents an abnormal protein of the enamel matrix and calcification, mainly occurring in that substance, might be an attempt at mineralization.

A total of 31 patients surgically treated for salivary mucoepidermoid tumor had a comprehensive follow-up. Two groups were classified as: 16 with favorable outcome (no recurrence or late recurrences at 5 yr postoperatively and still alive; 15 with poor outcome (local recurrences before 5 yr, metastases, lethal evolution in 11 cases). We evaluated nucleolar organizer in every case, using AgNOR count. The AgNOR count seemed better than histologic criteria for establishing the prognosis of mucoepidermoid tumors. It correlated significantly with the clinical course: a high count was principally found in lethal forms, low counts (less than 1.8) were always detected in patients with a good outcome.