Pleomorphic Adenoma with Exuberant Squamous Metaplasia and Keratin Cysts Mimicking Squamous Cell Carcinoma in Minor Salivary Gland

Salivary gland tumors, the second most common neoplasm of the mouth after squamous cell carcinoma, account for a significant proportion of tumors of the oral and perioral regions. An unusual case of adenoma presented as a solitary intraoral palatine mass in a 32-year-old woman is reported here. The tumor was interpreted as an unusual pleomorphic adenoma because of the presence of exuberant squamous metaplasia, clinically mimicking squamous cell carcinoma. Moreover, the presence of cystic structures filled with keratinized material was also salient feature. Pleomorphic adenomas may occasionally display focal squamous metaplastic changes; when extensive, it presents the potential for misinterpretation of the histology as indicative of well-differentiated squamous cell carcinoma.