TORONTO - A southern Ontario doctor is denying that she was responsible for a misdiagnosis of cancer that led to a woman having her breast unnecessarily removed.

Dr. Olive Williams filed a statement of defence in Windsor, Ont., denying "each and every allegation" against her in a $2.2-million lawsuit launched by Laurie Johnston, who underwent a mastectomy in the mistaken belief that she had cancer.

In court documents, the pathologist said she examined biopsy samples taken from Johnston and concluded in an Oct. 21 report that she had portions of fibroadenoma -- a non-cancerous lump -- in her left breast.

It's "not clear" whether Williams or a technician was responsible for the clinical diagnosis of "ductal carcinoma," she says in the document.

"Regardless, this information was an accurate description of the information provided by the referring physician," Williams writes.

"As Dr. Williams provided a clear and accurate pathological diagnosis, no cause of action is properly maintained against her."

Williams carried out the examination and diagnosis in a "careful, competent and diligent manner and denies that she was negligent," she writes.

Williams also denies that Johnston sustained the injuries and damages she alleges in her lawsuit -- calling them "excessive and too remote" -- and requests that the lawsuit be dismissed with costs.

Johnston claims in her lawsuit that she suffered medical complications from the surgery.

"What happened to her is quite serious," said Barbara MacFarlane, Johnston's lawyer.

"She not only lost a breast, she also suffered medical complications as a result of the surgery and it has significantly impacted the ability for her to use her arm, which has prevented her from working."

In a cross-claim, Williams is asking that her costs in this lawsuit be paid by the two Windsor-area hospitals where she worked.

Johnston is also suing her surgeon Dr. Barbara Heartwell, as well as the Hotel-Dieu Grace Hospital in Windsor, Ont., where the surgery took place, and the Leamington District Memorial Hospital.

None of the allegations in the lawsuit have been proven in court.

Williams' law firm declined to comment on the case or more recent allegations that their client made errors with six patients, partly because she had cataracts that blurred her vision.

An internal document drafted by the local health integration unit claims the hospital caught four of the alleged errors before any harm was done, but two patients underwent unnecessary surgeries.

According to the LHIN, the "internal issues briefing" document was based on information provided by the hospitals and would have been distributed to senior managers at the LHIN to alert them to possible stories in the media.

The document was dated Feb. 16, the same day a Windsor television station was planning to air Johnston's story.

Johnston's case, and that of Janice Laporte, whose healthy breast was removed by Heartwell, at the same hospital in 2001, have sparked a series of investigations.

The Ontario government, the College of Physicians and Surgeons of Ontario and Hotel-Dieu Grace Hospital all launched investigations into pathology or Heartwell.

Heartwell has stated in court documents that she was not negligent in Johnston's case but did acknowledge that she misread the final diagnosis in a pathology report.

Williams, whose hospital privileges were suspended in January, is also under investigation by the college.

MacFarlane declined to comment on the new allegations, but said Johnston is prepared to pursue her case.

"It's hard not to see it when it's in the paper, but I think her main focus right now is to try to get herself better, both physically and emotionally," MacFarlane said.

In Windsor, all parties named in lawsuits are required to discuss a possible resolution through a mediator, but no date has been set, she said.