system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 35-year-old man comes to the physician for evaluation of a neck mass and hoarseness. He has no history of major medical illness. Physical examination shows a 2.5-cm fixed, irregular thyroid nodule. His serum calcitonin concentration is elevated. The nodule is most likely comprised of cells that are embryologically derived from which of the following structures?
assistant
Lateral endodermal anlage