Six Months Ago I Had A Lumpectomy In My Left

Six months ago I had a lumpectomy in my left breast - tumor removed was less than half a centemeter and I was told margins were clear. Followed with 33 radiation sessions - chemo not required - also I am 72. Have been on Arimidex for two months now (finished radiation on Jan 5, 2016.) Two days ago, I went for my 6 month followup - diagnostic mammo both breasts and ultrasound of left breast - I had been feeling some "pain" only recently (perhaps less than two weeks) when I press my left breast - same breast remains "swollen" - I have been told this is not uncommon after radiation treatment. The tech who did the ultrasound very thorough and radiologist came into room and told me that the images on ultrasound suggest a debris-filled cyst and I am now scheduled for fine needle aspiration on 3/28.
I have looked up "debris-filled cysts"and read a lot about simple and complex cysts, etc. Would appreciate feedback as to doing more than fine needle aspiration depending on findings of this procedure. Thank you. Sandy