Swollen lymph nodes under are

I was diagnosed with DCIS Oct., 2008, and had a lumpectomy followed by radiation.  Now I have two swollen lymph nodes under my arm.  One was biospied and it came back as normal lymph tissue. Since the second one was found by the radiologist reading my mammorgram after the date of the first biopsy, I will have that one biopsied as well.
I was also diagnosed with thyroid cancer April, 2009, and with lung mets July, 2009. This cancer will be treated by RAI at the end of this month.
Your thoughts regarding what the swollen lymph node cause could be?
Thank you

[Cleveland Clinic]

Dear monica148:  There is no way to speculate on what this lymph node may be.  This may be benign as the other one was but there is no way to know without biopsy.