Polymorphisms in PTCH1 Affect the Risk of Ameloblastoma

Ameloblastoma is the most common odontogenic tumor, but the genetic nature of the changes in the tumor cells has been unclear. Mutations of CTNNB1 or PTCH1 are observed in many human tumors. Both CTNNB1 and PTCH1 are important in tooth development and are expressed in ameloblastoma. The aim of this study was to investigate whether genetic alterations of CTNNB1 and PTCH1 are present in ameloblastoma. We investigated 14 cases of ameloblastoma. The polymorphisms found in the ameloblastoma patients were further examined in a subsequent case-control study. We found a CTNNB1 mutation in one case of plexiform-type ameloblastoma. CGG triplet repeat-number polymorphism (CGG7/CGG8) in the 5′-untranslated region of PTCH1 was observed. The proportion of CGG8 alleles was significantly higher in the ameloblastoma group. The results of this study indicate a possible relationship between the CGG8 allele in PTCH1 and the risk for ameloblastoma.

Ameloblastic carcinoma ex ameloblastoma of the mandible with malignancy-associated hypercalcemia

Ameloblastoma is a rare, locally destructive, benign neoplasm of the jawbones, which arises from epithelium derived from the epithelial components of the developing tooth. Ameloblastic carcinoma is the term used to designate any ameloblastoma in which there is histologic evidence of malignancy in the primary tumor, regardless of whether it has metastasized. Most ameloblastic carcinomas are presumed to have arisen de novo, with few cases of malignant transformation of ameloblastoma being apparent. Hypercalcemia is the most common metabolic complication of malignancy. Although malignancy-associated hypercalcemia is often reported in association with other malignancies, it is exceedingly unusual in association with ameloblastoma, malignant ameloblastoma, or ameloblastic carcinoma. We describe a patient with multiple recurrences of ameloblastoma, with subsequent malignant transformation presenting with malignancy-associated hypercalcemia.

Inability to distinguish ameloblastomas from odontogenic cysts based on expression of blood cell carbohydrates

This study was designed to confirm the report by Vedtofte and coworkers that the epithelium of ameloblastomas can be distinguished from that of nonneoplastic odontogenic cysts by differences in expressivity of cell surface carbohydrates with blood group specificity. Immunoperoxidase techniques were used to study four radicular cysts, seven dentigerous cysts, six ameloblastomas, and six examples of plexiform unicystic ameloblastoma. No consistent differences were found in the expressivity of the blood group carbohydrates A, B, and H type 2 in the nonneoplastic odontogenic cysts as compared to the ameloblastomas. Consequently, the demonstration of these blood group carbohydrates is of no value in the differential diagnosis of nonneoplastic odontogenic epithelium from ameloblastomas, including especially the plexiform unicystic ameloblastoma, the pattern that so closely resembles hyperplastic odontogenic epithelium.

Distribution of blood group antigens A, B and H in ameloblastomas

The histologic distribution of blood group antigens, A, B and H was examined in ameloblastomas and normal mucosa from 15 patients. The blood group antigens were demonstrated with a semiquantitative immunofluorescence staining method. Blood group antigens A and B were absent in the ameloblastomas, whereas the spinous cells of the oral mucosal epithelium showed a positive reaction in correspondence with the patient's blood group. Blood group antigen H was demonstrated in 14 of 15 ameloblastomas from patients belonging to blood group A, B, AB or O. In the oral mucosal epithelium from these patients blood group antigen H in all cases was located to the cell membranes of the spinous cells. The present findings suggest that a difference in ability to synthesize blood groups antigen H and the blood group antigens A and B exists in the ameloblastoma.

Fibrinolytic activity in cystic lesions of jaw bones

The fibrinolytic activity in the tissues of cystic lesions of jaw bones was investigated by the semiquantitative method of Astrup. The specimens examined were ameloblastoma (9 cases), follicular cyst (8 cases) and radicular cyst (14 cases). High fibrinolytic activity was observed in ameloblastoma, while in radicular cyst the activity was variable. It is suggested that in radicular cyst inflammatory episodes play an important role in activating local fibrinolysis, while in ameloblastoma the tissue itself has a great capacity to induce locally activated plasmin.