Hi,
Discoloration of the areola, in the absence of other changes such as a rash, or underlying lumps, is not something very worrisome,especially if you are on birth control pills..What you have doesn't sound like cancer....on the other hand, any change needs some level of attention..When we see something unusual in or on the breast it's always best to let a doctor or dermatologist examine the abnormality...over the internet we can only just guess..but it's not a sure thing.Please call your doctor for an appointment,you will be reassured and have peace of mind.Best wishes and God Bless.