Nearly 800 tissue samples taken from patients in north Norfolk may not have been sent for testing for conditions which could include cancer, it can be revealed.
Some 780 patients who had minor skin surgery in Holt, Cromer or Fakenham over a four and a half year period have been asked to go for further tests after the blunder was uncovered by commissioners.
And the service, run by Holt Medical Practice and operating out of three different sites, has been stopped while investigations are under way.
It happened between January 2013 and June 2017 when the North Norfolk Clinical Commissioning Group (CCG) said they could not be sure best practice was followed in the community minor surgery service.
It was uncovered after clinicians realised during other NHS appointments that there was no record that samples were tested..
A spokesman said: 'We cannot be assured that all tissue removed during minor surgery was sent for histology, when tissue samples are examined under a microscope to see if any further treatment is required.'
Minor skin surgery includes removing moles and skin lesions - amongst other things - which are then sent off to be tested.
It can be performed by a GP and samples are then sent off for testing, but the CCG believes in some cases in north Norfolk these samples were instead destroyed.
Lesions can be removed if they are causing significant problems - such as repeatedly getting caught on clothing - or if there is any chance it could be cancerous.
But the CCG said they would not address which specific conditions the north Norfolk samples would have been tested for until all patients had been reviewed.
The CCG spokesman said affected patients - including those who had tissue removed without histology - were being contacted directly and invited back for follow up assessments, but he added this was a precautionary measure.
Dr Alistair Lipp, medical director for NHS England (Midlands and East) said: 'We would encourage everyone who receives an invitation for a further assessment to take up the offer.'
Dr Anoop Dhesi, from NHS North Norfolk Clinical Commissioning Group, added: 'We are very sorry if this causes people worry, but we think it is the right thing to do.'
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