What can I do about gynecomastia?

I took a bunch of different kinds of medication for depression and bipolar disorder several years back.

It caused weight gain and gynecomastia–that is, the development of male breast tissue, that I can’t seem to get rid of, even though I stopped taking meds and lost most of the weight.

I went to an endocrynologist and he said that surgery was the only way to get rid of it. Is there any way that working out can build muscle to at least somewhat hide it?