A Case of Basal Cell Adenoma of the Upper Lip

Abstract

Basal cell adenoma is a rare type of benign salivary gland tumor found most commonly in the parotid gland. We present a rare case of basal cell adenoma arising in the minor salivary gland of the upper lip. The patient was a 59-year-old Japanese man who visited our department in December 2012 with a chief complaint of a mass in the upper lip, which had increased in size over several years. A mobile, elastic, and relatively soft mass without tenderness was palpable in the upper lip region. The mucosa of the upper lip covering the mass was normal. Tumor extirpation was performed under local anesthesia. Histologically, the tumor had a capsule and was composed of islands of relatively uniform, monotonous cells. Immunohistochemically, the inner tumor comprised tubuloductal structures that showed strong staining for CK7, while the outer tumor showed weak staining for CK7. The outer tumor cells also stained positively for CD10 and p63. The MIB-1 (Ki-67) labeling index was extremely low. Basal cell adenoma was diagnosed based on these results. The postoperative course was uneventful 12 months after surgery and there has been no recurrence.

Basal cell adenoma of the parotid gland: Cytological diagnosis of an uncommon tumor

“…[ 1 ] Cytokeratin 5/6, p53, CD117, S100P protein and nuclear beta catenin are used to differentiate them from other basal cell neoplasms. [ 8 10 ]…”

Basal Cell Adenoma in the Parotid Gland: A Case Report of Rare Salivary Gland Tumor

“…However, the name of this tumor has been changed to "BCA" in the WHO salivary gland tumor classification since 1991. The most frequent location of BCA is the parotid gland (75%), followed by the minor salivary gland from the upper lip with 6%, and submandibular gland with 5% [6][7][8]. Clinically, BCA frequently occurs in people aged more than 50 years as a unilateral tumor with round or oval swelling.…”

“…The differential diagnoses of BCA are pleomorphic adenoma (PA), adenoid cystic carcinoma (ACC), and basaloid cell adenocarcinoma (BCAC). BCA has no rich stroma and the myxoid or chondroid elements as characteristics of PA [8,9,13]. Although ACC and BCAC have clinical and histological similarities with BCA, these malignant tumors exhibit invasive, unencapsulated growth into adjacent soft tissue, often with associated vascular or perineural invasion [7][8][9].…”

“…BCA has no rich stroma and the myxoid or chondroid elements as characteristics of PA [8,9,13]. Although ACC and BCAC have clinical and histological similarities with BCA, these malignant tumors exhibit invasive, unencapsulated growth into adjacent soft tissue, often with associated vascular or perineural invasion [7][8][9]. In addition to cytology differences, the high MIB-1 (Ki-67) labeling index helps distinguish ACC and BCAC from BCA [8].…”

Basal cell adenoma in the deep portion of the parotid gland: a case report

“…It is composed of relatively isomorphic basaloid epithelial cells, an abundant basal cell layer, and a distinctive basement membrane-like material. Notably, BCAs lack the myxochondroid tissue that is present in pleomorphic adenomas 6 . Clinically, the tumor tends to be an asymptomatic, slowly enlarging, freely mobile mass with a maximum diameter of less than 3 cm.…”