Metastasising Pleomorphic Adenoma: A rare case report of a pleomorphic salivary adenoma with synchronous cervical lymph node metastases

Abstract

Introduction: Metastatic Pleomorphic Adenoma (MPA) is a rare and controversial salivary gland neoplasm. Classified as a low-grade malignancy, benign histological features exist discordantly alongside their biological behaviour. An enigma; a benign tumour capable of distant metastases. Since 1942, there have been approximately 62 reported cases, though diagnosis is controversial considering their rarity and confounding histological interpretation. Pathogenesis is hypothesised to occur haematogenously through incomplete resection of primary PSAs or surgical disruption, aspiration of seeded tumour cells, or a lymphatic metastatic route. This is the first known case in the English-literature of an untreated minor salivary gland pleomorphic adenoma metastasising to a cervical node, demonstrating support for lymphatic dissemination.