Oncocytic differentiation in salivary gland tumours.

An oncocytic mucoepidermoid carcinoma and an oncocytic pleomorphic adenoma occurred in a 47-year-old male and a 75-year-old female, respectively. Both presented as asymptomatic parotid gland masses without evidence of facial nerve paralysis and were treated by superficial parotidectomy. There has been no evidence of recurrence or metastasis. Oncocytic change is rare in major salivary gland mucoepidermoid carcinoma with only two previously reported cases. Marked oncocytic transformation of pleomorphic adenomas can cause their confusion with oncocytomas. Recognition of oncocytic differentiation in various salivary gland tumours is important to avoid misclassification of these lesions.