Salivary Salvation

Question:  A 34 year old female presents with a parotid mass.  She has noted a steady increase in size over the last 3-4 months.  She notes that the mass has become somewhat tender over a similar interval.  She has no facial weakness, no overlying skin changes, and no adenopathy.  CT reveals a predominantly solid, homogeneously enhancing 2 cm tail of parotid mass.  Which of the above features is most concerning for malignancy?  [Answer will be posted with next week's new question]

Answer to last week's question, "Show Me A Sign" (August 29, 2016): 

Panendoscopy with directed biopsies.  If after doing so a primary site is not identified, many authors would perform ipsilateral or bilateral tonsillectomy with tongue base resection.