I had a similar problem on my arm. I take 1mg anastrozole once a day. I had switched to taking it before bedtime thinking to minimize any fatigue side effect. I then had hives over one of my forearm (I never had hives before). Since I did not want to scratch and cause broken skin, etc., I ran an ice cube over the area for some time until it stopped the itching. I have since switched back to noontime for my medication and no more hives. I do have some itching over the my breast and waist which I believe is from the radiation and not the anastrozole.