My experience has been weird, to say the least. About 7 years ago while in my very early twenties I took some Winstrol Depot. After coming off cycle my nipples began to itch and get puffy, which freaked me out since stanozolol doesn't aromatize.

This gear definitely looked legit so I don't think it was test or anything, from Zambon in Spain. Definitely got no water bloat, acne, or other test side effects, just hardness and vascularity.
Anyway, to make a long story short, an endocrinologist checked me out and said it should go away all on it's own. He was right. After about 6-8 months I had absolutely no sign of anything, and the lumps had been roughly pea-sized under each nip.
Thing is, I've had recurring tenderness in my right nip over the years. Sometimes it would get a bit puffy, sometimes just sore. All during this time my bf was pretty low, probably 12-16%, as I was naturally ectomorphic and skinny. The last two years my bf has shot up to 20% (I'm working on it!) during a lapse from training/diet and I have small man boobs/cones. The gyno has come back again on the right side, and has been sore now for at least a goddam year. Pea-sized lump under there.
I'm thinking that my hormones may have been affected by the following things:
1. Physiological stress from working shift work
2. Junk food diet - burgers are probably laced with hormones and increased fat=increased estrogen.
3. Increased DHT as my hairloss started around the same time.
Now I'm no expert by any means, I only know what happened to me. Hopefully by cleaning up my diet and training hard I can burn off the bf to see what I got under there and if I need to cut it out or not.