A case of basal cell carcinoma of the buccal mucosa with black pigmentation

Basal cell carcinoma (BCC) is a malignant tumor that most often occurs in the head and neck, particularly near the midline skin region. In recent years, several reports have documented the occurrence of BCC in the trunk, axilla, and scrotum. However, BCC arising from the oral mucosa is rare. Through a literature review, we identified 13 cases of BCC arising from the oral mucosa, reported mainly by European and American clinicians. Moreover, 3 of these cases were reported to arise from the buccal mucosa. Herein, we report a case of multifocal superficial type BCC with black pigmentation. An 85-year-old woman was referred by her dentist for evaluation of erythema with black pigmentation in her oral cavity. Histopathology revealed a palisading arrangement of basal-like cells and decreased space between the surrounding tissues at the epithelium. Differentiation from peripheral ameloblastoma was required. Therefore, we performed immunohistological staining. The lesion showed positive staining for Ber-EP4 and negative staining for KL-1. From these results, in combination with a clinical examination, superficial type persistent BCC (in accordance with the World Health Organization classification) was diagnosed. The patient declined surgery but was monitored for a period of over 5 years since the initial diagnosis. During this time, the lesion showed slow growth.