Lynne McConnell, 51, from Glasgow, started wearing the close-fitting bras 15 years ago, after being measured at a shop.
She said they always felt too tight, but numerous shop assistants told her they were fine - and she kept wearing them until she noticed a lump in the middle of her chest.
The pea-sized bump grew to a 4x4cm rock-hard mass - directly over where the midpoint of the bra sits on her chest in a matter of days - and she sought medical help.
Lynne was diagnosed with a painful cyst which had to be cut out, leaving her with an open wound which took three months to heal.
Lynne, who works in pharmaceuticals, claims her surgeon said the wired-bra had put pressure on a gland, which blocked, and caused the cyst to develop.
British Skincare Foundation dermatologist Dr Adil Sheraz confirmed tight clothing, like underwired bras, are known to cause cysts.
Lynne, who now lives in Brighton, said: "There is a lack of awareness about these types of bras.
"Something has clearly gone wrong and all I want is for people to learn from what has happened.
"I don't want anyone else to go through what I have. It really affected my self-esteem for a long time.
"I couldn't wear a bra for weeks and I try to take pride in how I look. It wasn't nice at all."
Lynne, who has 34GG breasts, said she was fitted by experts in a shop, but had to return numerous times over the years to complain of tightness.
She said she often put tissue underneath the bra to add comfort.
But she said when she complained, bra fitters said the garments fitted adequately, so she kept wearing them.
"The staff just said that's how they are supposed to fit," she said.
In June last year she noticed a "pea-shaped" lump which became very painful.
The lump grew and she phoned 111 and was told to go along to A&E at Brighton and Sussex Hospital, on June 16.
Lynne was given antibiotics and doctors suggested the lump could be an abscess caused by infection.
But the tablets didn't work and when Lynne went to her local breast clinic on July 4, she was in "agony" and was unable to wear a bra.
The doctor at Brighton's Park Centre for Breast Care said it was a cyst and it was removed immediately under local anaesthetic, she said.
Lynne said: "It had become particularly uncomfortable to wear a bra and the lump was growing quickly.
"By the time I went to the breast clinic it was really painful. I went in at 3pm and left within two hours. The surgeon just cut it out there and then.
"It was just too tight. I always said it was too tight but they just told me that's how it should fit.
"It was uncomfortable but I just listened to them. The staff insisted that's how tight they need to be.
"The surgeon said the pressure of the bra caused the gland to get blocked.
"I was always told to have it really tight. I raised concerns that they were too tight but I was just told that's the size that fits me."
She was left with an 4cm open wound that couldn't be stitched up, needed dressing daily and took three months to heal properly.
Lynne, who has been married to wife, Honor, for eight years, said the scar is still tender and she has to wear wireless sports bras.
"It was absolutely awful," she said.
"I felt miserable all the time and it really affected my confidence. That hole was the first and last thing I thought about everyday."
Lynne wrote to the retailer to complain and was put in touch with the company's legal team, who told her last month the bras or fitting were not to blame.
According to dermatologist, Dr Adil Sheraz, tight clothing - like underwired bras - are known to cause cysts.
The British Skincare Foundation consultation said sacs containing semi-fluid material, which looks like cottage cheese, can form on the skin as a result of wearing overly tight clothes.
Dr Adil Sheraz, consultant dermatologist and a spokesperson for British Skin Foundation said: "Cysts ares a benign growths that form under the skin.
"They are lined with epithelium, a layer of cells, that often forms the 'sac' which will contain semi-fluid material, which often has the appearance and consistency of cottage cheese.
"They are often defined based on their location, for example pilar cysts often from on the scalp.
"Cysts can be inherited or acquired. Inherited conditions, such as Gardner's syndrome, can result in multiple cysts.
"Cysts form when cells start multiply inwards rather than being shed on the surface.
"Why some people form cysts is not entirely known however they can often be caused by a blockage at the site of a hair follicle opening, as a result of a blocked pore or even injury to the skin.
"Occlusion of pores which may occur from pressure or tight garments could potentially cause formation of cysts."