A question about breasts to the ladies (specifically the transwomen)?

No! It's not about my soon to be lobbed off tissues, this is a question for a friend of mine.

She's transitioning, and it has come to her attention that there is a mass in her breast, sitting under her armpit and her nipple is producing a brown discharge.

Her doctor is already pretty much saying breast cancer without so much as test results. He says it "feels like a tumor".

She's been undergoing HRT since March '08... 1.25 mg of Premarin and 200 mg of Spironolactone.

Does anyone have any sort of ideas (other than the C word) as to what might be going on? I'm of the opinion she might have a cyst or two... does that seem likely?

And yes, she is getting it checked out proper. This is just a "in the mean time so as to not worry" sort of asking around the internet.

Thanks to everyone who answers with helpful answers. The trolls will be fed to the kitties!