Intraoral Basal Cell Carcinoma: Report Of 2 New Cases With Literature Review

Intraoral basal cell carcinoma (IOBCC) is an extremely rare entity that is often confused with the peripheral ameloblastoma (PA). Basal cell carcinomas are thought to arise from pluripotential basal cells present within surface epithelium and adnexal structures, so theoretically they can arise within the oral cavity. Most of the well-documented cases arise from the gingiva. Many of the early cases reported as IOBCC actually represent PA. We present 2 cases displaying histologic, immunohistochemical, and clinical features characteristic of an IOBCC. The histologic features of IOBCC that help separate it from a PA include prominent retraction artifact, tumor arising from surface epithelium, scattered mitotic figures and apoptotic cells, presence of mucoid ground substance, and tumor infiltrating widely throughout the connective tissue. Clinically, IOBCCs resemble carcinomas, compared with the benign and innocuous appearance of the PA. IOBCCs typically present as surface ulcerations varying from rodent ulcer to an ulcerated erythroplakic appearance. This contrasts with the classic “bump on the gum” appearance of PAs, with usually intact surface and appearing as small, discrete, sessile, exophytic lesions. In the more recent literature, Del Rosario et al. and Koutlas et al. described IOBCC with positive immunoreactivity of only the neoplastic basal cells for the antiepithelial antibody Ber-EP4, a cell surface glycoprotein. Normal skin or oral epithelium, PA, and squamous cell carcinomas do not stain with Ber-EP4, a very important distinguishing factor separating these entities.