Pope Leo XIV has said he will have an operation to remove a lump on his lung this week, the first time a pope has made a personal medical announcement of this kind.
The 71-year-old is otherwise healthy and is known for his love of sport.
Here is what we know.
When will the operation take place?
The pope said the operation was planned "in the coming days" and the Vatican press office said it would be at the beginning of the week, without giving a date.
Italian media have speculated that the operation could be on Tuesday, although the pope is due to preside over a Mass in St Peter's Basilica on Wednesday morning with Church leaders from around the world and there have so far been no announced changes in his schedule.
The Vatican press office has said doctors expect the pope's recovery to take around a week. That would make it possible for him to leave for his visit to Latin America as planned on 6 November.
The 11-day trip will take him to Uruguay, Argentina and Peru, a country close to the pope's heart as he worked there as a missionary for two decades and took on Peruvian citizenship.
What is a pulmonary nodule?
A pulmonary nodule is a small growth of tissue in the lung. Most are benign, meaning they are non-cancerous. But a small percentage can be an early stage of lung cancer.
Most small nodules cause no symptoms and are only discovered during checks for other health issues.
Larger nodules can cause shortness of breath, chest pain and persistent coughing, sometimes with blood.
The operation is normally carried out under general anaesthetic with the patient breathing through a tube.
Where will the operation take place?
The operation is expected to take place at Rome's Gemelli hospital, where popes are usually treated.
Pope Leo XIV's predecessor Francis spent weeks there for treatment before his death last year.
John Paul II, head of the Church from 1978 until his death in 2005, was treated nine times at Gemelli, Rome's largest hospital, and spent a total of 153 days there.
He quipped that the hospital was like "Vatican number three."
The Vatican ultimately created a top-floor apartment at the hospital site, accessed by a long corridor guarded by Italian and Vatican police.
Besides the pope's room, the suite reportedly includes a meeting room for medical staff, a kitchen, bathroom and rest areas.
There is also a small chapel.