Women are frequently advised to check themselves for lumps to detect and prevent breast cancer, but there are also other, often overlooked, hints that a deadly illness is developing beneath the surface.

In July 2016, English writer Claire Warner posted a Facebook photo that highlighted one of those hidden symptoms. 

The picture quickly went viral as more and more women spread the word about a little-known symptom of breast cancer: a subtle dimple.

“The small purplish bruise is where I had a biopsy taken,” Warner wrote. “...after surgery, chemo and radio therapy, I've every hope of being cured.”

Warner was grateful to catch the signs thanks to a similar social post shared by another woman with breast cancer.

Back in 2015, a woman named Lisa Royle shared her own photo of a breast dimple that developed in the early stages of breast cancer. Inspired by Royle's personal story, Warner recognized this symptom early on. “I can't feel the lump, even now that I know it's there,” Warner wrote. “I'm not ill. My only symptom is this dimple.”

Warner’s post, which was recently reported by Indy100, sparked so much online discussion that she opened a Twitter account for her left breast, @OfNoSpecialType, where she documents her battle against cancer, which now includes chemotherapy treatment. 

Since Warner started sharing her cancer journey on social media, at least one other woman claims she was able to detect breast cancer in herself during the early stages by watching out for these more subtle symptoms: skin irritation and dimpling.

By daring to share intimate pictures of their own bodies, women like Warner and Royale helped save lives. “I saw Clara Warner’s picture...to my surprise I had it too. Same Dimple, same position, also in the left breast,” Facebook user May Ibáñez wrote in Spanish.

The American Cancer Society recommends that women over the age of 45 get annual mammograms to screen for breast cancer, dropping down to once every two years after a decade of healthy results. But for younger women, routine mammograms are often more costly than helpful. Instead, the ACS suggests checking oneself regularly for the following symptoms: breast pain or swelling, unexpected nipple discharge and dimpling, irritation, redness, scaliness, or thickening of the skin anywhere on the nipples or breasts. Sometimes a new dimple is just a quirk. But these women proved how important it is to stay familiar with one's own body.