Kylie Armstrong, a 45-year-old textile designer in Melbourne, Australia, told BuzzFeed News that she cried when she was diagnosed with breast cancer in February.
It was a "huge shock," she said.
Breast cancer does not run in her family and she didn't feel a lump anywhere leading up to the diagnosis.
She did, however, notice a cluster of dimples on her right breast.
"I wasn't overly concerned but thought I should probably get it checked out as it was different to normal," she said.
She saw her doctor the day after she noticed the ripples. The doctor couldn't feel a lump but agreed that it looked abnormal and sent Armstrong to get a mammogram and ultrasound.
The tests showed Armstrong had breast cancer.
Dr. Deborah Capko, a breast surgeon at Memorial Sloan Kettering Cancer Center, told BuzzFeed News that dimpling is one of breast cancer's subtle signs.
"Obviously the first thing you're looking for when doing a breast exam is lumps, any masses," she said. "But masses are one of the things you can find. You're also looking for dimpling."
Dimpling in the breast can occur when a cancer mass grows onto the ligaments in the breast and tugs at the skin, said Dr. Capko.
"It is often the first sign a person sees before they feel a lump," she said.
Capko said dimpling does not always mean that a person has breast cancer. She said dimpling can also be a sign of breast infection, which is much more common than cancer. But either way, it is important to get it checked out.
"Because [dimpling] is such a subtle finding, it may be missed the first time," she said. "That's the most important thing is just not to ignore it."
Armstrong said she and her family were devastated by the news. She first posted her experience on Facebook in February to warn her friends and family about this inconspicuous sign of cancer.
"When I was telling my friends and family everyone asked, did I feel a lump?" she said. "I didn't, the GP didn't. None of them had any idea that dimples could be a sign that there was cancer inside the breast. I hoped that by putting the post up it might help at least one person."
The post has since been shared over 250,000 times and garnered over 9,500 comments, including many people who shared their own breast cancer stories that began with dimpling.
"Just over a year in recovery so there is light at the end of the tunnel sometimes," another said.
Armstrong's post has even led women to more aggressively seek out the cause of breast dimpling they see on their own bodies.
Armstrong has since had surgery to remove the cancer mass in her breast. She said she never "imagined [the post] would go viral."
"I found my cancer early," she said. "The outlook is good for me. If I had ignored the dimples, it might be a different story."