Salivary Gland Heterotopia, a Clinical and Pathological TNM Staging Challenge - Carcinoma ex Pleomorphic Adenoma Arising in a Parotid Lymph node

Introduction: Heterotopia is the presence of a particular tissue / tumor at a non-physiological / ectopic site. The study primary goals: To review the current data investigating heterotopic, normal appearing, and diseased salivary gland tumors, in lymph nodes. To describe the meticulous pathological investigation and multidisciplinary decision-making process of a heterotopic carcinoma ex pleomorphic adenoma arising in an intra-parotid lymph node. Materials and Methods: A literature search in the "PubMed" database using key words "carcinoma ex pleomorphic adenoma", "parotid lymph node", "salivary gland" and "heterotopia" was conducted. We describe the thorough pathological investigation and clinical decision-making process, focusing TNM staging system limitations. Results: A few case reports presented either normal appearing salivary tissue, benign tumors or low and high-grade salivary malignancies arising in lymph nodes. We present the investigation, controversies and treatment decision process of a 46-year-old man with CXPA in intra-parotid lymph node. Conclusions: The staging scheme does not distinguish between nodal spread and primary tumor arising in a lymph node. Multidisciplinary input regarding prognosis and follow-up plans, may consider heterotopia differently from the usual pattern of nodal spread.