Italian police said the mother asked the woman, identified only as Luisa, 26, to cover her breasts while sunbathing at a public beach in Anzio because the process of applying cream "troubled her sons aged 14 and 12," The Daily Telegraph reported Thursday.
The mother called police when the woman refused her request.
"The fact a file has been opened is compulsory following the complaint but I can't imagine any judge in 2010 convicting a woman for sunbathing topless," said Gianluca Arrighi, a lawyer for Luisa.
Arrighi said topless sunbathing on public beaches is legal in Italy except where banned by local laws.
Police said the incident is under investigation.
"The patrol went and took her details and she argued, still topless, that she could see no harm in what she was doing as it was a public beach," a police spokesman said. "We have opened a file on committing an obscene act as we are committed to following the complaint. From what I heard she was very attractive."