Oral basal cell carcinoma: Report of a case with immunohistochemical findings

Basal cell carcinoma (BCC) arising from oral mucosa is a controversial or nonentity. Ameloblastoma, peripheral ameloblastoma (PA), and basal cell adenoma (BCA) are included in the differential diagnosis of such neoplasms. A possible example of oral BCC is presented that originated on the posterior mandibular mucosa and gingiva of a 67-year-old woman. It recurred six times after local excision during a period of 8 years and, most recently extended to include buccal mucosa. Tissue samples of the tumor were evaluated recently with the monoclonal antibody Ber-EP4 (Dako, 1:80) that has been used in differentiating pulmonary adenocarcinoma and mesothelioma. It reportedly distinguished cutaneous BCC and squamous cell carcinoma (SCC). This antibody reacts with two nonkeratin, epithelial glycoproteins of 34 and 39 kDa present predominantly on cell membranes and, to a variable extent, in cytoplasm of several non-cutaneous epithelial cells and neoplasms originating from them. Each specimen of the present neoplasm was evaluated and compared with examples of oral mucosa, skin, oral SCC, PA, ameloblastoma, and cutaneous BCC. Positive staining of neoplastic basal cells of the oral BCC was obtained. Staining involved cell surfaces and, occasionally, cytoplasm of neoplastic cells. Examples of PA and ameloblastoma failed to react with this antibody and only a focus of a few neoplastic spinous cells of OSCC exhibited faint staining. Immunohistochemical staining of normal oral mucosa and skin was negative including basal cells. Only portions of sweat ducts were stained. Selected immunohistochemical evaluations support the inclusion of oral basal cell carcinoma within the differential diagnosis of appropriate oral mucosal neoplasms and Ber-EP4 may be helpful in diagnosis.