Tumor of the Parotid or something else?

I was diagnosed with a Pleomorphic adenoma. I first notice the mass after having a bad chest infection that moved up to my sinuses. I was shaving after I started feeling better and notice the mass then. I did not notice the mass before and it has not gotten any bigger for the last 3-4 months. I had the biopsy done and it came back benign but they told me that it was the pleomrphic adenoma and needed to be removed sergicly. I was wondering if there would be a possibility of of a misdiagnosis since I did not notice the mass before and they told me that they are a slow growing tumors. The mass seemed to have grown only when I was sick and has not gotten any larger in size from what I can tell since. Is there any other kinds of growths that can mimic a tumor of the parotid that just go away over time and do not require surgery? Thanks for your time and I look forward to hearing from you!!