Sebaceous lymphadenoma is a benign tumour of the salivary gland. Sebaceous lymphadenoma is a benign tumour of the salivary gland. Sebaceous lymphadenoma is a tissue diagnosis, e.g. salivary gland biopsy. It may be confused with a number of benign and malignant neoplasms, including Warthin tumour, mucoepidermoid carcinoma and sebaceous lymphadenocarcinoma.