It started 2 years ago, it started to decline, now its coming back again -- worse. I just hit me that it isn't a cyst or breast cancer. And only recently has it become obvious, rather than very subtle. Mostly just the left side. It did start after I fell onto a table corner. But it clearly is not just bruising. And that would have been long gone by now.
I am also wondering what is known about the effect of opioids, specifically morphine and fentanyl, or gynecomastia. I've read they increase prolactin and decrease testosterone, but haven't found much specifically about their relationship to gynecomastia.