Peripheral ameloblastoma of the gingiva: the importance of diagnosis.

BACKGROUND Peripheral ameloblastoma is an extremely rare epithelial odontogenic tumor, limited to the soft tissues of the gums or oral mucosa. Although the lesion is benign, it may be locally aggressive. METHODS The present study describes the case of a 31-year-old male presenting a firm, symptomless tumor mass of irregular appearance and measuring approximately 12 mm in diameter, located in the distal zone of 4.7. RESULTS An excision biopsy was performed. The lesion was covered with hyperplastic squamous epithelium, with islets of epithelial cells located at subepithelial level. The cells in the peripheral zone adopted a palisade distribution, and presented the appearance of a lax reticulum at central level. A fibroblastic stroma was observed between the islets. The diagnosis was peripheral ameloblastoma. CONCLUSIONS Although the origin of the lesion remains unclear, it is able to recur and undergo malignant transformation. Consequently, peripheral ameloblastoma should not be viewed as a harmless mass.