Laura Tabatabai, MD1, Walid Khalbuss, MD, PhD2
1Department of Pathology, University of California-San Francisco, San Francisco, California
2Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
Clinical History: The patient is a 52 year old woman who presents with a painless 2.5 cm mass that has been slowly growing for the past 3 years. Fine needle aspiration is performed.
What is your diagnosis?