"It doesn't see what the reason behind it is, it's just automatic," she wrote. "It can't see that the picture I posted earlier, may actually save lives.
"'I'm obviously totally gutted, as it took a lot to share my picture with you, because I'm so body conscious, and fretted about sharing at all."
Rowena had been travelling in New Zealand and was catching up with a friend on the phone when she felt a lump in her breast.
She was first diagnosed with cancer in 2009, has made a BBC documentary Before I Kick the Bucket, and uses her Facebook page to keep followers up to date with her condition.
She was determined to share the image because, before her diagnosis, she was unaware what signs to look for - such as inverted nipples, rash and puckering - and didn't want the knowledge to die with her.
"I wasn't out to offend anyone. It looks like something out of a medical journal," she told The Independent.
"Posting that photograph was the bravest thing I've done. It's so personal; I was petrified."
She also questioned whether the site would have taken down the photo if she'd posted a picture of cancer in her big toe to show what it looked like.
Following the removal of her initial post, she shared a new version of the photo with a smiley face covering the nipple.
"What you are looking at is a rash on the chest, around an imaginary nipple," she explained.
"In my case it is definitely cancer. In this example it's also quite severe."
"Breast cancer can present itself in this way - not necessarily around the nipple, but anywhere in the chest or breast area.
"It may also start small and look like nothing, but any rash on the breast or chest that doesn't go away, or seems to be growing should be investigated.'
Rowena was flooded with supportive messages from followers who criticised Facebook for taking down her photograph and praised her for being brave enough to share it.
Tanya Ryan, the mother of another breast cancer patient, said: "Am glad you put that picture up. Women need to be aware of what to look for.
There is no more that can help me when cancer works out how to resist this chemo I'm on, and takes over again.
"As you know my daughter is is only just 22 and gone through breast cancer. She only felt a lump but you're right it can form itself in different ways, so needs to be addressed."
"Still cannot believe they took it down," Helen Mandy Jeremiah commented. "Yet, they'll happily allow hideous videos of terrorist propaganda and of abused animals, which I and many others find offensive. You go girl."
Karen Saffy said she'd even shared a picture of her own nipple on Rowena's page as a gesture of solidarity, while Brian Hanlon said he "admired her bottle".
Rhuanedd Richards simply wrote: "Well done Rowena - absolutely stupid decision by Facebook. You really are a remarkable woman."
Sheryl Jones said the idea of Rowena's post being offensive was "beyond humanity" and encouraged her to keep sharing.
Julie Dyne congratulated Rowena and said that Facebook should be "embracing" people like her.
Meanwhile Gordon Scott Russell encouraged everyone to "paste it and post it".
Rowena was 33 when she was diagnosed with breast cancer in July 2009.
Recalling the symptoms, she said: "It felt like an electric shock when I touched it and seemed to grate against my pectoral muscle, but I was too young to think of something as sinister as cancer."
She was diagnosed with triple negative cancer, which affects about one in five people with breast cancer, and cannot be treated using hormone therapy.
After gruelling chemotherapy, she was told she was cancer free and returned to work.
However in 2013 the cancer returned and she was given six months to live.
She defied doctors' predictions, but her health is now deteriorating and she's having radiotherapy to prolong her life.
"I'm officially on my last treatment option. I've exhausted all chemos available to me," she said.
"There is no more that can help me when cancer works out how to resist this chemo I'm on, and takes over again."
-Daily Mail
