Supplementary Material for: Primary Basal Cell Adenoma of the Lacrimal Gland: a rare case.

Basal cell adenoma (BCA) is a rare benign tumor of the salivary gland, reported to account for 1-3% of all salivary gland tumors, and is the third most common benign salivary gland tumor after pleomorphic adenoma（PA） and Warthin's tumor. We present the first case of a primary BCA of the lacrimal gland, an extremely rare condition, which is very similar in clinical presentation to PA of the lacrimal gland tumor. An 18-year-old male patient experienced mild right ptosis for 3 years, without diplopia or pain. Orbital CT showed partial bone erosion, and MRI showed a 16 × 18 × 25 mm lobulated, well-defined mass. Anterior orbitotomy was performed to totally remove the entire lacrimal gland tumor along with its surrounding periosteum. Histopathological exams revealed a biphasic pattern of solid and cribriform, with no evidence of neuropathy, vascular invasion, or invasion of surrounding tissues. The cell membrane and many nuclei of the tumor cells was positive for β-catenin. BCA is a very rare tumor of the lacrimal gland, but complete resection is the effective treatment. Postoperative follow-up is necessary due to the possibility of malignant transformation.