Massive metastasising Carcinoma ex pleomorphic adenoma of submandibular gland presenting as a neck mass: a clinical mimicker of a thyroid malignancy

Carcinoma ex-pleomorphic adenoma (CXPA) is a rare, destructive, poorly understood malignancy of the salivary gland. CXPA is described as a carcinoma arising from a primary (de novo) or recurrent benign pleomorphic adenoma (PA). It is most likely to occur within the major salivary glands, mostly parotid gland and usually occurs in patients in the 6th– 8th decades of life, approximately one decade later than patients with pleomorphic adenoma. Malignant changes in PA have been related with long tumor duration, tumor recurrence, radiation therapy, advanced age, a large tumor size and location in major salivary glands. It often poses a diagnostic challenge to clinicians as well as pathologists. Treatment for Ca ex PA frequently involves an ablative surgical procedure which may be followed by radiotherapy. Overall, patients with Ca ex PA have a bad prognosis. Accurate diagnosis and aggressive surgical management can however increase their survival rates. I present this case to highlight its clinical relevance and diagnostic challenges it posed when FNAC was used as a primary investigative modality.