Diagnosis: Pleomorphic adenoma
• Different types of metaplasia (e.g., squamous and sebaceous) sometimes occur in various salivary gland tumors.
• Pleomorphic adenoma sometimes displays squamous metaplasia, as in this case.
• Basal cell adenoma and basal cell adenocarcinoma can show squamous (as well as sebaceous) elements.
• Squamous and sebaceous differentiation have been described in epithelial-myoepithelial carcinoma.
• Squamous differentiation does not usually occur in adenoid cystic carcinoma. This generality is sometimes useful in terms of differentiating adenoid cystic carcinoma from various mimics.