Ian Paterson denies causing wounding with intent to nine women and one man at two West Midlands hospitals.
He told a court Joanne Lowson was given "all the options" before she asked for a lump, later found to be benign, to be removed.
The operation in 2010 left her with a "significant deformity" in a breast.
The court heard Ms Lowson first had an operation to remove a lump which turned out to be benign in 2009.
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She returned to see Mr Paterson, from Castle Mill Lane, Ashley, Altrincham, in 2010 "obviously concerned" about another lump in the same area.
Mr Paterson told the court that scans and his own assessment of the lump had proven "discordant - they don't agree with each other".
"Clinically and ultrasonically, it's a little suspicious," he said.
"I've clearly told her the only pathology we have for this lump is benign.
"She was that concerned, and the options are clearly laid out for her."
Tests on tissue after the operation - which left Ms Lowson with the deformity in "the visible cleavage area" in her left breast - showed it was benign, the court heard.
The charges Mr Paterson, who worked at Heart of England NHS Trust and Spire Healthcare, is facing relate to procedures carried out between 1997 and 2011.
The court heard how investigations into his alleged wrongdoings left him with "high anxiety levels" and he had seen his GP and psychiatrists at least seven times between 2011 and October 2014.
He described himself at the time as "very anxious and not coping".
The trial continues.
A breast surgeon accused of carrying out an unnecessary operation on a woman has told jurors the surgery was "the patient's choice".