Polymorphous adenocarcinoma of the parotid – An uncommon site of occurrence

Abstract

Polymorphous low-grade adenocarcinoma is a neoplasm of the minor salivary glands and is malignant in origin but is indolent in nature. Currently, this neoplasm is documented and known as polymorphous adenocarcinoma (PAC) by WHO Classification of Salivary Gland Tumors (2017). Of all the salivary neoplasms, minor salivary gland neoplasm accounts for 9%–23%. Very rarely, it involves major salivary glands such as parotid, submandibular, and sublingual in <5% cases. It may develop either de novo or from pleomorphic adenoma. PAC mimics some benign as well as malignant neoplasms. Histopathological features alone cannot diagnose PAC due to the overlapping features with other neoplasms, and so immunohistochemistry is essential to confirm the diagnosis and hence aids in the proper management of PAC. We report a case of PAC arising from parotid gland in a 52-year-old male treated with facial nerve preservation.

Keywords

• immunohistochemistry
• parotid
• polymorphous adenocarcinoma
• salivary gland