Case ReviewsEctopic Mucoepidermoid Carcinoma A Pitfall on Fine-Needle Aspiration BiopsyChute, Deborah J. MDAuthor Information From the Department of Pathology, Cleveland Clinic, Cleveland, OH. Reprints: Deborah J. Chute, MD, Department of Pathology, Cleveland Clinic, 9500 Euclid Ave, L25, Cleveland, OH 44195. E-mail: firstname.lastname@example.org. The authors have no funding or conflicts to declare. AJSP: Reviews & Reports: January/February 2015 - Volume 20 - Issue 1 - p 3-6 doi: 10.1097/PCR.0000000000000071 Buy Metrics Abstract Mucoepidermoid carcinomas (MECs) can rarely arise outside normal major and minor salivary gland sites in the head and neck. Ectopic MECs are believed to arise from ectopic salivary gland tissue, which most often occurs in cervical lymph nodes, but can rarely be found in other sites throughout the head and neck. Fine-needle aspiration biopsy of MECs at ectopic sites can be confusing, as the clinical differential diagnosis usually does not initially include a salivary gland tumor. In addition, MEC is one of the most common causes of a false-negative fine-needle aspiration biopsy, particularly for low-grade tumors, which are frequently extensively cystic and may be acellular. Features that would support a diagnosis of ectopic MEC on fine-needle aspiration biopsy include abundant thick extracellular mucin, mucinous epithelium, and epidermoid cells. Awareness that salivary gland tumors can occur at unusual sites is key for the pathologist evaluating the aspirate to arrive at the correct interpretation. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.