Branchial Cleft Remnant Masking as a Thyroid Mass in an Adult Patient

A 53-year-old woman presented with a 4-cm left thyroid mass discovered during physical examination. She reported no history of head or neck radiation and no family history of thyroid carcinoma. However, she had a long history of hypothyroidism, treated with daily 88 mcg levothyroxine. She had no history of weight loss or other systemic symptoms over the past year and denied any compressive symptoms, dysphagia, odynophagia, or hoarseness. Neck ultrasound showed a heterogeneous and atrophic right thyroid lobe measuring 2.2 × 0.4 ×1.1 cm.