The picture has been shared tens of thousands of times.
"She only posted the picture to Facebook to make family and friends aware of what she'd found," her husband, Craig Thomas Royle, told BuzzFeed News.
In the picture, which her husband took for her, a small dent can be seen on the underside of Royle's left breast.
"This all that I found on my boob. Very subtle dimples underneath that could easily be missed when we're all rushing round getting ready in a morning."
She urged women to take a moment out of their day to check for signs of breast cancer: "Please take time to look at your boobs. It could save [your] life ?"