Ewing sarcoma of the thyroid: Report of 2 cases and review of the literature

Background. Neuroendocrine tumors of the thyroidencompass a wide differential diagnosis. The most common is medullarythyroid carcinoma. One must consider other possibilities when aneuroendocrine thyroid tumor is calcitonin negative. We report 2 cases ofEwing sarcoma of the thyroid and discuss the differential diagnosis andworkup of a calcitonin-negative neuroendocrine tumor of the thyroid.Methods/Results. This is a retrospective review of 2 patients diagnosedwith Ewing sarcoma of the thyroid and a review of the literature.Conclusions. Ewing sarcoma of the thyroid is an exceedingly rarediagnosis, but should be included in the differential diagnosis for athyroidal neuroendocrine lesion (especially in the absence of calcitonin).The use and interpretation of immunohistochemistry (IHC) andfluorescent in situ hybridization are essential in making the correctdiagnosis. V C 2013 Wiley Periodicals, Inc. Head Neck 35: E346–E350,2013 INTRODUCTION Neuroendocrine lesions of the thyroid are not uncommonoccurrences that encompass a wide differential diagnosiswith medullary thyroid carcinoma (MTC) being the mostcommon. This diagnosis is confirmed with the presence ofcalcitonin, either via serological or immunohistochemicaltesting. A neuroendocrine tumor in the thyroid can becomeclinically complex if calcitonin is absent. Other primaryneuroendocrine lesions must be considered, as well as me-tastasis to the thyroid. Of course, treatment must be tailoredto the exact diagnosis. In this article, we discuss 2 cases ofthe very rare diagnosis of primary Ewing sarcoma of thethyroid. The differential diagnosis for thyroid neuroendo-crine lesions and their workup are emphasized, as well astreatment of Ewing sarcoma.