A breast surgeon advised one of his patients to have a double mastectomy or risk "full-blown cancer", despite tests not showing any sign of malignancy, a court heard.
Ian Paterson, 59, then wrote to Frances Perks' insurers with a false diagnosis in order to justify an operation carried out for "no good reason whatsoever", prosecutors claim.
The surgeon is standing trial after denying 20 counts of wounding with intent against nine women and one man relating to procedures he carried out between 1997 and 2011.
Jurors have previously heard claims he carried out completely unnecessary operations for "obscure motives" that may have included a desire to "earn extra money".
Prosecutor Julian Christopher QC told Nottingham Crown Court Ms Perks was referred to Paterson in 1994 aged 35 after finding a lump in her breast after her mother and sister had died from cancer.
He said: "Because of the family history, she was kept under close surveillance and on a number of occasions over the next 10 years, Mr Paterson removed lumps from one or the other of her breasts, which in each case were found to be benign."
More than a decade later, Mrs Perks went to see Paterson again after the discovery of another lump, with examination of tissue around the lump not showing any sign of malignancy, the prosecution said.
Mr Christopher told the jury: "(She was told) it was time to be thinking of having a mastectomy and that, if she did not, she would end up with full-blown cancer.
"He said that if it were him, he would have a double mastectomy.
"He wrote to her insurers, stating that she had recently been diagnosed with multi focal LCIS in her left breast and that she had a very high statistical probability of having disease in the other breast. (This is) quite wrong."
Paterson, who was formerly employed by Heart of England NHS Trust and also practised at Spire Healthcare, then carried out the mastectomy on her left breast in November 2008, a procedure that the prosecution claim was "another unjustified and unnecessary operation".
Jurors were told: "Mrs Perks describes getting over the operation as awful. She has to spend two weeks where she had to sleep sitting up, it was extremely painful, and she had ongoing problems with the area of her stomach from which tissue had been taken for the reconstruction, which were not put right until she had a further operation in 2012.
"She thought that all of this was necessary because otherwise her life was at risk. That was what she believed as a result of what she had been told by Mr Paterson.
"In fact it was quite unnecessary."
Joanne Lowson was left with a "significant deformity" in the cleavage area after Paterson wrongly reported test results to her and her GP to carry out operations, the prosecution claimed.
Mrs Lowson was first referred to the surgeon in March 2009 after she found a lumpy area on her left breast - with a mammogram and ultrasound showing "nothing suspicious", Mr Christopher said.
He told jurors Paterson said to her GP the results were "largely" benign and that although there was "nothing sinister going on", she was determined to have it removed as she previously had a malignant melanoma.
He said: "To Mrs Lawson and her husband, he described the area as 'unstable but not cancerous at this stage', and that he could not guarantee that it would remain non-cancerous.
"Unsurprisingly, they understood that the area represented a risk and accepted Mr Paterson's suggestion that he should remove the lump. Mrs Lowson says she would not have done so had she known that the tests had shown no abnormality."
The results of the operation were all clear, but Paterson told Mrs Lowson that she had to remain on top of it and have regular mammograms - which reinforced her impression that she had "done the right thing" in having the lump removed, the court heard.
Mrs Lowson underwent another operation in 2010 after the surgeon claimed tests on a recurrence of the lump were "a little suspicious", the court heard.
Mr Christopher said: "Once again, it was unnecessary. Unfortunately, these two operations left Mrs Lowson with a significant deformity in the visible cleavage area of the left breast that required subsequent correction and thus a third operation.
"She has been left with numbness and very little feeling in her left breast. All three operations were the result of Mr Paterson having wrongly reported the test results to her, her husband and her GP and using language like 'unstable' when there was no evidence that there was ever any increased risk of the development of cancer."
The last of the 20 counts Paterson is facing relates to Rachel Butler, who was operated on in 2005 aged 30. She returned to see Paterson six years later because a lump beside her left nipple had returned and was painful. The surgeon told her she "had to have" an operation to cut all the ducts off around the nipple "because she was at a high risk of contracting cancer if the lump kept returning", the prosecution said.
The operation in January 2011 had complications, including the wound bleeding for several weeks, it is alleged. Mr Christopher said: "Before the operation, Mr Paterson had sought to justify it by pretending that the ultrasound showed a very inflamed duct system.
"Afterwards, he justified it by telling her GP that the pathology report looking at the tissue that had been removed showed lots of inflammation.
"The report makes no mention of inflammation at all and the prosecution say the operation was totally unnecessary."
The court heard Paterson was interviewed by arrangement in January 2013, when he read a prepared statement saying all surgical procedures he had undertaken were "appropriate and necessary".
"He denied any allegations of inappropriate or unnecessary surgery or bad faith for the purposes of financial gain or for any other purpose, and he said that he found any suggestion that he would propose unnecessary procedures for financial gain as abhorrent," Mr Christopher said.
He was again interviewed in September 2014 where he refused to answer questions.
Paterson, of Castle Mill Lane, Ashley, Altrincham, Greater Manchester, denies all counts.