A woman had part of her top jaw cut away after being wrongly diagnosed with cancer of the mouth.

The surgeon who treated her says the misdiagnosis happened after a lab worker dropped two samples on the floor and mixed them up.

She is the sixth woman the Herald on Sunday has discovered to be affected by errors made in pathology laboratories since we started an investigation a month ago.

Nelson oral surgeon Dr Iain Wilson said his 63-year-old patient suffered facial swelling and sinus infections after having a tooth implant last year.


Wilson took an oral biopsy sample, which was sent to Medlab Dental in Dunedin and tested for cancer.

The results were positive and the woman underwent a hemimaxillectomy to remove the right side of her upper jaw.

Bone and artery veins were taken from her lower leg and used to reconstruct the woman's jaw, Wilson said. "Her donor wound site got infected and she had difficulty walking," Wilson said.

She was later given the heartbreaking news that tissue taken during the surgery showed no sign of cancer and her initial specimens had been swapped with another patient after the pathologist accidently dropped her test pot.

"I am being asked to believe two samples were being processed simultaneously and the pots were simultaneously dropped," Wilson said. "I can't for the life of me understand how you can get tissue samples mixed up," Wilson said.

"I am astonished and horrified by these lab mix-ups."

He said the case was before the Health and Disability Commission and the patient had consulted a lawyer about compensation. Medlab Dental could not be contacted.

A senior pathologist says more mistakes are inevitable if pathology processes and funding structures continue to lag behind international standards.


Auckland senior surgical pathologist Tony Bierre claimed cancer pathology was in the midst of a crisis and urgent action was needed to prevent further errors which had life-changing consequences for patients.

Last week, PathLab Waikato pathologist Ian Beer admitted he had made an error which resulted in a woman unnecessarily having her breast removed. It was the third similar case the paper had discovered.

Beer said pathologists were under pressure to meet a five-day deadline for breast cancer diagnosis and he wanted the deadline extended to 10 days.

But Bierre said the request would lower standards and patients deserved to know their results within 24 hours. "When you get a senior pathologist like Ian Beer calling for us to accept a standard that is so far below what is internationally recognised, you wonder what on earth is going on," Bierre said.

He claimed the problems lay in funding structures and "factory-styled" operations.

Pathology is carried out in two separate practices: anatomical, which tests tissue for cancer; and clinical, which tests cells and blood for other issues. Laboratories which combined anatomical and clinical pathology were "factory-styled operations".

"It is like putting the manufacturing of baked beans in the same factory as high-tech engineering."

He was also keen to see funding streams split for the two branches of pathology testing.

Biopsy inquiry widened

The government has extended its inquiry into botched biopsies to cover all laboratory processes relating to biopsies.

The inquiry comes in the wake of a Herald on Sunday investigation which revealed at least three women had breasts removed after wrong cancer diagnoses.

Last week, Associate Health Minister Jo Goodhew asked chief medical officer Don Mackie to look for similarities between the cases, once the three district health boards had completed their investigations.

Goodhew widened the inquiry this week to cover all laboratory processes for biopsies.

"The Ministry of Health has convened an expert advisory group," Goodhew said.