Peripheral ameloblastoma of the lower molar gingiva: a case report and immunohistochemical study.

Peripheral ameloblastoma (PA) is a rare extraosseous odontogenic tumor with histological characteristics similar to those of the common intraosseous ameloblastoma. Two questions regarding PA remain: its histogenic origin and how to differentiate between PA and intraoral basal cell carcinoma. We describe a patient with PA. The result of immunohistochemistry showed cytokeratin (CK) 7-, CK14+, CK19+, AE1/AE3+, CAM5.2-, 34 β E12+, epithelial membrane antigen-, Ber-EP4-, p53-, p63+, and low Ki-67, that was similar to those of 4 cases of intraosseous ameloblastoma. Our results suggest that a PA originates from odontogenic epithelial remnants, rather than from the oral epithelium.