Metastatic neuroendocrine tumor of the esophagus with features of medullary thyroid carcinoma.

A 41-year-old female presented with a pedunculated mass in the upper esophagus and bilateral lymphadenopathy. Biopsies suggested a neuroendocrine tumor, possibly carcinoid, and ensuing imaging revealed cervical lymph node metastases. The esophageal mass was removed endoscopically and discovered by pathologists to closely resemble medullary thyroid carcinoma (MTC) on immunohistochemistry staining. Following surgery, further work up demonstrated very high serum calcitonin levels, suggestive of medullary thyroid carcinoma, however the thyroid gland was normal on ultrasound. The patient underwent a neck dissection to remove the lymph node metastases and subsequently her calcitonin levels dropped to 0 ng/mL, indicating remission. It appears that the primary tumor was not in the thyroid, but in the cervical esophagus. The thyroid has appeared normal on multiple ultrasounds without any detectable nodules or masses. This is quite a unique case because this patient presented with a tumor resembling medullary carcinoma of the thyroid that presented as a pedunculated mass in the cervical esophagus. The actual final diagnosis of this mass in the cervical esophagus was neuroendocrine tumor (NET), consistent with a carcinoid tumor, not ectopic MTC. This case report highlights that calcitonin-secreting tumors outside the thyroid should not lead to erroneous recommendations for thyroidectomy.