Miss Dean was born with her left forearm missing
A woman claims clothing firm Abercrombie & Fitch made her work in the stockroom because her prosthetic arm did not fit the shop's image.
Riam Dean told an employment tribunal she felt "diminished" and "humiliated" by the incident at its Saville Row store in central London.
The 22-year-old law student is suing for disability discrimination and seeking up to £20,000 in damages.
The company said she "exaggerated" the impact of the experience on her life.
Miss Dean, who was born with her left forearm missing and wears a prosthetic arm, said she was granted special permission to wear a cardigan to cover the join in her arm.
But she told the tribunal she was later removed from the shop floor and made to work in the stockroom because the cardigan did not adhere to the strict dress code.
Miss Dean told the tribunal, in central London, she felt "taunted" when her manager told her she could return to the floor of the firm's flagship store if she removed the cardigan.
She said: "I felt personally diminished, humiliated and could not argue a point I could never win."
She told the hearing she would have stayed with the company until her law qualification was complete, had she not been "bullied" out of her job.
Miss Dean added that when she left the company she "wasn't the same person".
"I was always prepared for children to be curious about my disability, but to be faced with adult bullying, no-one could have prepared me for such debasement," she said.
Genevieve Reed, a close friend of Miss Dean, told the tribunal: "The girl who once felt invincible started to question whether this was the first of a series of obstacles she would come up against to her disability.
"To watch my extraordinary friend's character and spirit crushed by a large corporation was heartbreaking."
But Akash Nawbatt, representing Abercrombie & Fitch, argued Miss Dean had deliberately played up the effect of her experiences.
He referred to a medical assessment Miss Dean underwent to secure disability funding for university.
The report described her as "becoming socially-isolated" and unable to use public transport because of anxiety.
However, Mr Nawbatt told Miss Dean: "Just as you are exaggerating in the report, you are exaggerating what happened at Abercrombie and the effect it had on you."
Miss Dean has just finished her final exams at Queen Mary, University of London.