What Causes Outbreak Of Acne On Withdrawal From Anastrozole?

Hi, I am now taking chemo for my second bout with breast cancer. The last one was an estrogen positive tumor, and this one is both estrogen and HERS2 positive. My oncologist took me off my anastrozole. I think he will be putting me on another estrogen blocking drug. But since I went of the anastrozole I have pimples like a teenager. Is this common when stopping it?