"People thought that if they spoke to me, my birthmarks would jump at them."

Just about every adult can remember what it was like to be the target of childhood bullies. But one model and Instagram influencer endured so much verbal abuse while growing up, she actually became a recluse.

Now, Yulianna Yussef is no longer in hiding. Instead, she's clapping back at those who relentlessly made fun of her because of the birthmarks that stretch from her back, down her middle, and along parts of her arms and legs. And take that, haters: Her anti-bullying, body-positive message is earning her major praise on Instagram.

“In three words—I was bullied,” Yussef said in a new interview with the UK publication Mirror Online. "I was a Dalmatian, a giraffe, a cow. I was dirty and people thought that if they spoke to me my birthmarks would jump at them."

Yussef’s birthmarks come from a rare condition called congenital melanocytic nevus (CMN), which causes light brown to black marks on the skin, according to the National Organization for Rare Disorders. They appear at birth and can become thick and hairy as a child develops.

Some people with the disorder have one or two marks, while others, such as Yussef, can have several that cover large parts of the body. CMN isn't just a cosmetic issue. People who have it are at a greater risk of developing melanoma or neurological diseases. A common side effect is extremely itchy skin.

As the bullying over her birthmarks got worse, Yussef became a recluse in her home city of Warsaw and only left her home at night. She wrote on Instagram: "I would just ask 'why me?'" She added that she didn't think anyone would ever "love a girl with a black and hairy back."

Finally, Yussef had enough and decided to make a change. "I was so tired of hiding and being afraid of people, of their reactions and actions. I was hating myself for the weakness and that I felt so much pity towards myself. I then understood that nobody would help me just myself, to bring me up with my confidence.”

Yussef realized that most people didn't know anything about her condition—and that made them fearful of her. She thought that if she educated people about CMN, then she could help others with it.

With this in mind, she took to Instagram and began showing photos of herself, discussing her past as a bullying target and promoting body positivity. Now, her Instagram account is just shy of 100,000 followers. Thanks to the positive feedback she has received from them, Yussef now feels beautiful and confident.

In one Instagram post, she wrote this: “I love my skin, I love my cellulite (yes I have), I love my stretch marks (have them as well ), I love my birthmarks. And Yes, I feel like a perfect angel with my “imperfection, “And how about you?”