Pope Leo XIV has been admitted to the hospital for surgery Tuesday to remove a small growth on his lung, in what is his first stay in hospital since the start of his pontificate.

The 71-year-old pontiff told the crowd gathered in St. Peter’s Square on Sunday that doctors had discovered a “nodule” on his lung, which he had been advised to have removed. A nodule is a mass of dense tissue that is often benign. Leo said on Sunday that the growth had been detected “at a very early stage” and was “well-contained.”

The surgery will take place Tuesday afternoon at the Agostino Gemelli University Policlinic hospital in northwest Rome, a private medical facility that has a long association with the Vatican. The hospital has a special suite of rooms for the pope on the 10th floor, which Pope John Paul II famously dubbed “Vatican three” during his frequent stays there – St. Peter’s being Vatican one and the papal residence Castel Gandolfo, Vatican two. Pope Francis also spent an extended period there early last year when he was treated for pneumonia.