A Winnipeg pathologist has been placed on leave after officials found that as many as nine complex medical cases may have been misdiagnosed.

The Winnipeg Regional Health Authority and Diagnostic Services Manitoba are now conducting a review of the cases.

According to a WRHA news release, the DSM reviewed 35 recent cases and found problems with seven.

That led to a wider, random, review of a further 107 cases where two more were red-flagged. The majority of the cases were cancer related.

Health officials say so far their review has shown they haven't missed any cases of cancer --  the errors were in the diagnosis of the severity of the disease. They also say making a diagnosis isn't straightforward and different pathologists will have different interpretations of a tissue sample.

The WRHA is now informing the patients involved and their doctors about the issue.

Doctors will then have to talk to their patients about possible changes in treatment. The WRHA said some patients will not require any changes despite the problems with their pathology report.

The WRHA said those patients needing treatment changes will get priority in the system.

"We might find we've been overly cautious and there's no problem -- or we might find there is a problem," Dr. Amin Kabani, Manitoba's Diagnostic Services told CTV News.

The pathologist in question was placed on leave on March 27, but officials aren't releasing a name. Some say that he is a senior pathologist.

An external pathologist is reviewing all complex cases related to this pathologist from the last year. The review is expected in the next few weeks.

The DSM and the WRHA are also conducting what's called a Critical Incident Review to determine what can de done to improve the process and prevent it from happening again.

WRHA has established a dedicated phone line 788-8004 to address questions and concerns from the public.