The Betsi Cadwaladr Health Board 'should review cases' of patients who have been treated for moles at a GP surgery in Colwyn Bay, according to a North Wales coroner.
It comes after one patient had one removed without it being tested and later died of cancer.
Philip Rafferty visited his doctor with a mole on his chest in 2008 - instead of it being removed and tested it was chemically frozen off. Three years later he was diagnosed with malignant melanoma and died last year at the age of 51.
Mr Rafferty returned to the Rysseldene Surgery on a number of occasions after the mole was first removed with pain and pea-sized lumps in his arm pit and shoulder.
One of his requests towards the end of his life was that other patients be recalled for proper biopsy testing.
Deputy coroner Nicola Jones granted Phillip's wishes and used her powers under Rule 43 of the Coroners Rules 1988 to write a report on the case to prevent other deaths taking place in similar circumstances.
Mrs Jones requested the health board recall patients with similar symptoms who may need further consultations.
His widow Lesley says the coroner issued what she considers to be a stark and serious message to all GPs in the UK.
Paula Bridge, head of clinical negligence at Ralli Solicitors which represents the Rafferty family and said, "The coroner has made the right decision."
Rysseldene Surgery has expressed its condolences to the family and says it will address any recommendations from the coroner.