My husband has lots of fatty tumors. In total I think the last time I checked he had 25 of them. Fatty tumors are caused by rapid weight gain or loss. They are not serious unless they grow around muscles or put pressure on the spine which can cause pain and sometimes numbness. Yes your doctor can tell by feeling a tumor if it is just a fatty tumor or not, I had one in my upper abdomen and even though it was causing minor pain and was told it wasn't cancer, I still had it removed and had it tested. To make yourself feel better about it it is best to get another doctor to look at it and possibly have it removed for testing.