DCIS 3 years ago, lumpectomy and radiation, new cyst found

Cysts are very common. If it's a simple cyst, there is no concern at all. Even if it's a complex cyst, a 6 month follow-up is usually what's done.

If the cyst is palpable (i.e. the mass can be felt by hand), then to Melissa's point, a fine needle aspiration can be done. It's a simple 2 minute in-office procedure. However if the cyst is small and can't be located by hand, there really is no reason to have a biopsy; monitoring the cyst should be sufficient. I had DCIS too, and I have a few cysts that I've had few years. The simple cysts aren't monitored at all, although every year they are noted on my mammo and MRI reports. I also have a complex cyst that has been monitored on a 6 month basis for a couple of years (the tech locates it on an ultrasound and measures it to be sure that it's the same size as always). My complex cyst has been completely stable through all my checks and my radiologist told me that after my next mammo and ultrasound (coming up in November), no further monitoring will be required. After this amount of time, if it was a problem, something would have happened by now. With complex cysts, I believe the risk of cancer is only 0.03%.

If the discoloration and flattening of your nipple doesn't clear up, that would be something that's more important to follow up on.

working mom, I had a similar situation and it was caused by scar tissue necrosis, which seems pretty common, but it will ease you're mind to have it checked I had an MRI.

sis, I hope it turns out to be nothing!