Basal Cell Adenoma Occurring at an Uncommon Site: Masquerading as a Mucous Retention Cyst

Basal cell adenoma is a rare benign salivary gland neoplasm with a monomorphic basaloid tumour cell pattern, most commonly occurring in the parotid. We present a rare case of basal cell adenoma arising in an uncommon site of minor salivary glands of the upper lip in a 74-year-old male. The patient presented with a mobile, non-tender mass on the upper lip, which was gradually increasing in size. The tumour was excised under local anaesthesia with a clinical diagnosis of mucous retention cyst. Histopathological examination revealed a circumscribed tumour composed of mixed tubular, membranous and trabecular patterns of basaloid cells with lumen of tubules containing eosinophilic material. Immunohistochemically, the tumour showed positivity to SMA and BCL2 while it was negative for CD117. Basal cell adenoma was diagnosed based on these results. The postoperative course was uneventful and there has been no recurrence