A 38 year-old woman presents to your office in early July complaining of fever and anterior neck pain. It feels like a sore throat, which gets aggravated by swallowing and refers to the ear. She reports that she has been suffering from a flu-like illness for the past two weeks. A detailed review of systems reveal rapid heart rate, nervousness, anxiety, difficulty sleeping, dysphagia, weight loss, increased appetite, sweating and tremor. Family genetic history is significant for HLA-Bw35. On examination, her heart rate (HR) is 110 beats per minute (bpm) and blood pressure (BP) is 147/87 mm Hg, and she is afebrile. You note a firm, tender thyroid gland with two nodules and a 2/6 systolic ejection murmur on cardiac examination. Her skin is warm and dry. There is a fine resting tremor when she spreads her fingers. Laboratory findings show elevated serum T3 and free T4; suppressed serum TSH; absent antithyroid antibodies, high ESR and low uptake of radioiodine. Fine needle aspiration biopsy shows lymphocytes and multinucleated giant cells among the thyroid follicles. Which of the following is the most likely diagnosis in this patient?
