Metastasising Pleomorphic Salivary Adenoma: A Rare Case Report of a Massive Untreated Minor Salivary Gland Pleomorphic Adenoma with Concurrent Ipsilateral Cervical Node Metastases

Salivary gland tumours constitute approximately 1–5% of all human neoplasms. Pleomorphic adenoma (PA) is the commonest benign neoplasm affecting the parotid gland most often (> 75%), followed by the submandibular gland (13%), then the palate (9%). Metastasising pleomorphic adenoma (MPA) is extremely rare. The effects can be severe and a reported 40% of MPA patients die with disease. This case represents the first known case in English literature of an untreated minor salivary gland PSA of the palate metastasising to an ipsilateral cervical node. We report a 61 year old female who presented with a large tumour occupying the palatal vault, and cervical neck mass. The oral tumour was believed to have been growing over four decades. The patient died eight months following surgical resection. Of known cases, male: female ratio is 35:51 and the mean age at diagnosis is 49.2. Most commonly, MPA is detected in bone 33.3% (n = 29), lung 31% (n = 27) and cervical lymph nodes 20.7% (n = 18). Thorough reporting is deemed essential to further understand the biological differences of non metastasising and metastasising PAs, treatment outcomes, prognosis and survival rates.