Review Question - QID 109568

A 40-year-old Japanese woman presents to her primary care doctor with complaints of headache and palpitations. She is a business analyst who was recently promoted to a senior role at her company. She has noticed that she feels more anxious at work and at home with her kids. She has been trying to eat to keep her strength up, but thinks that tea and soup are easier to digest given her anxiety. She said that years ago she had her tonsil size reduced by radiation because "that's what the doctor recommended." Her temperature is 98.6°F (37°C), blood pressure is 134/91 mmHg, pulse is 112/min, and respirations are 21/min. On physical exam, there is a palpable, non-tender swelling in the front of her neck that moves with swallowing. There is no cervical lymphadenopathy. An ultrasound of the thyroid reveals a large, hypoechoic nodule shown in Figure A. The doctor refers the patient to a specialist for a fine-needle aspiration biopsy. What is the most likely diagnosis?