@heartloverdrm
As SwitchableSusie its impossible to give you an answer about the histology of any lump without investigation , but a round lump with a well-defined outline is, in most cases, benign. That said in 10 to 20% of all cases, a round and well-defined lump may correspond to a cancer.
Ultrasound is a painless procedure that uses sound waves to make images of the inside of your body. The sound waves bounce off surfaces in your body, and the "echoes" are recorded and transformed into video or photographs.
You really don’t need to do to anything to prepare for a breast ultrasound.
You’ll be asked to change into a hospital gown, so you may consider wearing a two-piece outfit on the day of the test so that you only need to remove your top.
You’ll lie on a padded examining table during the test.
A small amount of water-soluble gel is applied to the skin over the area to be examined. The gel doesn’t harm your skin or stain your clothes.
A probe that looks like a little paddle is gently applied against the skin.
You may be asked to hold your breath briefly several times.
The test takes about 10-20 minutes to complete.
https://www.breasthealthuk.com/breast-cancer-screening-services/breast-ultrasound