Metastasizing pleomorphic adenoma: a fascinating enigma.

Among salivary gland neoplasms, metastasizing pleomorphic adenoma (MPA) constitutes an extremely rare group of tumors. The present paper reports a case of pleomorphic adenoma (PA) in submandibular gland that, after more than 30 years of initial treatment, recurred and metastasized to ipsilateral neck lymph nodes and parotid gland. In an attempt to elucidate the malignant behavior of metastasizing pleomorphic adenoma, we performed Ki-67, p53, p16, and bcl-2 immunohistochemistry staining of our case sample. Many immunohistochemistry staining studies have been done on malignant salivary gland tumors. However, to the best of our knowledge no immunohistochemistry staining of the aforementioned markers has been previously performed on metastasizing pleomorphic adenoma.