You know, I am trying to find out. I am on arimidex and just had a military random drug test. I am told that it isn't something sought after. Now on a steroid test it might. I am told no since it's primary use is for breast cancer treatment. It's not something commonly used. They tend to test for steroids itself. Arimidex is a non-steroidal AI which might save you.
Perhaps someone else can shed some light?