A large basal cell adenoma extending to the ipsilateral skull base and mastoid in the right parotid gland: A case report.

Background: Basal cell adenoma (BCA) is a rare benign tumour that has unique histological characteristics and primarily arises in the parotid glands. According to published reports, nearby tissue destruction by BCA seems impossible.

Case Summary: We presented a case of a 54-year-old woman with a mass in the deep lobe of the right parotid gland involving the ipsilateral skull base and mastoid. The patient exhibited gradual right facial swelling but no other obvious symptoms. Combined resection of the total right parotid gland and partial skull base excision were performed. The biopsy conducted before the surgery and sections cut from intraoperatively obtained tissues were not definitive for identifying the character of the neoplasm. A final diagnosis of tubular BCA without malignant elements was established based on postoperative pathology results and immunohistochemical analysis. The tumour did not recur during the 12-mo follow-up period.

Conclusion: A diagnosis of BCA can only be established based on a histopathological examination after an excisional biopsy, and tubular BCA should carefully be considered as a destructive type.