A family doctor told a patient who later died that a lump in his groin was benign and would improve.
Health and Disability Commissioner Anthony Hill said in a report released today the unnamed GP breached patient rights.
The patient had a non-dangerous mole removed from his thigh two years before finding a lump in his groin.
His unnamed GP ordered an ultrasound that indicated the lump was not malignant but it also suggested a follow-up test in a month's time.
The GP told the patient the lump was benign but failed to convey the uncertainty or organise the follow-up.
When the lump grew and became painful five months later, in late 2012, another ultrasound revealed a malignant melanoma. The patient died the following year, prompting a complaint from his wife, who said his deterioration was traumatic.
"It was a very bad experience for the patient and for his family," he said.
"It is important that in New Zealand we are aware of melanoma, we are aware of risk factors and that we are responding appropriately as things change around us."
Mr Hill said the doctor was too casual and showed a lack of critical thinking. He urged all patients to ask for a copy of any reports about them.
"It's a classic example of information that, had it been shared with the patient, would have equipped the patient to better participate in the care being provided," he said.
"Patients need to know the significance of results in order to ensure that they and the doctors take appropriate action."
Mr Hill said it was the GP's duty to provide services with reasonable care and skill, and he recommended the Medical Council consider carrying out a competency review of the doctor.