A cystic basal cell adenoma arising in the upper lip: A case report and review of literature

Basal cell adenoma (BCA) is a rare type of benign tumor of the salivary gland. This study presents a BCA case of a 74-year-old Japanese female referred to our hospital with a mass in the upper lip. The 22 × 15 × 13 mm tumor was observed as a round, bluish-violet, elastic, hard mass. T2-weighted magnetic resonance images revealed a heterogeneous hyperintensity mass in the upper lip. This lesion was diagnosed clinically as a benign tumor of the upper lip and was surgically resected with the inclusion of healthy tissue under general anesthesia. The cut surface of the lesion showed a cyst-like structure with the solid area projecting into that cavity. Moreover, histologically, the solid area exhibited basal cell-like cells forming small and/or large cribriform cell nests and a partially palisading-arrangement on the periphery of their cell nests, with connective tissue hyalinized in the stroma. Immunohistochemically, the tumor cells were positive for AE1/AE3, S-100 protein, and vimentin. From these findings, the diagnosis was BCA. There have been no recurrence 6 years postoperatively.