Ameloblastoma
Ameloblastoma is the commonest clinically significant benign epithelial odontogenic tumour, with locally aggressive behaviour and a high recurrence rate. It makes up about 1 percent of all jaw tumours and cysts, and arises in the mandible in 80 percent (mainly the molar ramus region) and maxilla in 20 percent. It is more frequent in Africa, where it often presents in the third and fourth decades and sometimes in children, and has a high burden in East Africa.
Types: conventional (solid or multicystic, 86 percent, aggressive), unicystic (15 percent, younger patients, often associated with an unerupted tooth, with mural or luminal growth), peripheral (extraosseous, gingival, 1 percent), and metastasising ameloblastoma (benign histology with lung and lymph node metastasis, very rare).
Conventional ameloblastoma harbours BRAF V600E mutations in 60 to 80 percent (mandible) and SMO or other MAPK pathway mutations in the maxilla. Histological patterns are follicular and plexiform. It spreads by infiltration of cancellous bone far beyond the radiographic margin (up to 1 cm), and recurrence is 50 to 90 percent after curettage, below 5 percent after wide resection. Malignant transformation (ameloblastic carcinoma) is rare.
