What's on the Inside Matters Most

Question:  A 50F patient presents with a palpable neck mass.  She states that she noted it suddenly one morning while washing her face and neck.  Her outside physician examined this and noted a rubbery 1.5 cm low anterior mass on the left.  An outside ultrasound demonstrated a single cystic appearing mass that appeared separate from the thyroid gland.  Calcium, parathyroid hormone, and thyroid function tests were normal.  Fine needle aspiration biopsy demonstrates acellular aspirate.  What additional test(s) could you consider using a repeat fine needle aspiration biopsy to finalize a diagnosis?  [Answer will be posted with next week's new question]

Answer to last week's question, Take My Breath Away (November 9, 2015): 

Any tumor pressing on the ipsilateral vagus nerve or recurrent laryngeal nerve can cause recurrent laryngeal nerve palsy and therefore must be ruled out.  Therefore, imaging from the skull base to the aortic arch must be obtained.  This is best performed with an MRI, but a CT with contrast is also reasonable.