Polymorphous low-grade adenocarcinoma of the parotid salivary gland.

Polymorphous low-grade adenocarcinoma is an unusual tumor that has been described as occurring in the minor salivary glands, particularly of the palate. To our knowledge, there is only one previous report that has documented the occurrence of this type of lesion in the major salivary glands. We describe an elderly patient with polymorphous low-grade adenocarcinoma arising in the parotid gland that was originally diagnosed as carcinoma ex pleomorphic adenoma.