David Musyj (Moo-SHAY), who heads Windsor Regional Hospital, says the surgeon was Dr. Barbara Heartwell, who was linked to two past mistaken mastectomy cases.
But Musyj says the error was not her fault and the surgeon at Hotel-Dieu Grace Hospital in Windsor did nothing wrong.
The patient had a lumpectomy in mid-April but when the tissue was tested it didn't match the original biopsy — and it was later discovered the patient was incorrectly identified.
Musyj says a pathologist made a "human error" by attributing a correct diagnosis to the incorrect patient.
He says the pathologist — who has not been named — has taken a voluntary two-week leave.
Musyj adds that when policies and procedures are not followed at his hospital, it's his responsibility.
"So I am responsible, nobody else."
The other patient later got the correct diagnosis when the error was discovered, Musyj said.
He stressed the error came from the pathology department, not the surgeon.
"It's not her fault. In no way is this her fault, whatsoever. She did everything 100 per cent correctly based upon the information she had."
The pathologist involved is "distraught and remorseful" over what has happened, Musyj said.
Heartwell was one of two doctors named in a lawsuit by a Leamington, Ont., woman whose healthy breast was removed in 2009, in the mistaken belief it was cancerous.
Laurie Johnston settled her lawsuit earlier this year. Details of the settlement were not disclosed.
The lawsuit had named Heartwell and pathologist Dr. Olive Williams, as well as Hotel-Dieu Grace Hospital, where the surgery took place, and the Leamington District Memorial Hospital.
Johnston's case, and that of Janice Laporte, whose healthy breast was removed by Heartwell at the same hospital in September 2001, prompted a series of investigations.
The College of Physicians and Surgeons of Ontario launched investigations into Heartwell and Williams, but it did not refer Heartwell's matter to its discipline committee.
Hotel-Dieu Grace Hospital restored full privileges to Heartwell, but it suspended Williams last year and she has since resigned.
(CKLW, The Canadian Press)