The actor's hairline was revealed when he leaned forward to eat his lunch, while he was enjoying a break on his yacht in Italy's picturesque isle of Capri.
According to the Daily Mail, the Oscar-winner, conscious of the patch, touched the back of his head and then donned a trilby to workout on his onboard treadmill.
The newspaper also revealed that Cage's 23-year-old wife, Alice, was on hand to pass over the trusted trilby and provide moral support for the clearly sensitive actor.
Cage spent most the time reading, said the report.
The actor recently purchased a castle worth five million pound in the Somerset city, his third in a list of 14 properties around the world altogether estimated to be worth 33 million pound.