The 54-year-old woman died of a likely embolism on Thursday, two days after undergoing the unnecessary operation, the reports said.
An autopsy was being carried out and investigations have been launched.
This incident is the latest in a string of incidents involving the Italian health system over the past few months.
In February, the organs of an HIV-positive woman were transplanted into three patients in Florence.
In May, an elderly man died in a hospital near the southern Italian city of Taranto while in intensive care after he was given oxygen instead of anaesthetic gas in a tube mix-up.
In June, doctors performed an abortion on a woman pregnant with twins in Milan, taking out the healthy child instead of the one with Down's Syndrome.