Pope Leo XIV is scheduled to have an operation in the “coming days” to remove “a localised nodule” in his lung that was “detected at a very early stage.” It is the first medical event of his 17-month papacy and the first time a pope has made a personal medical announcement of this kind. Speaking on Sunday during his weekly address in St Peter’s Square, the 71-year-old pontiff said doctors found the nodule during “recent checkups” and believed intervention was best option.“I have decided to undergo surgery to have it removed,” he said.What is a pulmonary nodule?Pulmonary nodules are round areas in the lung where the tissue is abnormally dense. They are usually non-cancerous; most small ones cause no symptoms and are discovered only during checks for other health issues.However, a small percentage can signal an early-stage lung cancer. The risk is higher in older people, smokers and those with a family history of the disease.  If the nodule is cancerous and removed at an early stage, the prognosis is “excellent,” and surgery alone may be sufficient treatment, Stephen Liu, a lung cancer expert at Georgetown’s Lombardi Comprehensive Cancer Center, told the Associated Press. How common are they and what causes them?Lung nodules are very common and appear in roughly one-third to one-half of all chest CT scans or X-rays. Diagnoses are increasing as medical imaging technology and routine scans become more widespread. Pulmonary nodules fall into two main categories: cancerous (malignant) and non-cancerous (benign). Benign nodules, the most common type, can result from lung infections, such as pneumonia, or from inflammation. Malignant ones are caused by lung cancer or by cancer that has spread elsewhere in the body. How is the surgery and the recovery?The operation to remove a nodule is normally carried out under general anaesthetic, with the patient breathing through a tube.The Vatican said the pontiff will undergo surgery early this week and is expected to remain in the hospital for about a week afterwards to recover. The pope will be treated at Rome’s Agostino Gemelli Polyclinic, a private non-profit Catholic teaching hospital. The facility has a special apartment set up for pontiffs, which includes a meeting room for medical staff, a kitchen, a bathroom, rest areas and a small chapel.  Pope Leo’s immediate predecessor, Pope Francis, was treated there during a long illness, prompted by a respiratory crisis before his death in April 2025. Who is in charge while the Pope is in surgery?The Vatican has no specific rules governing who takes over if a pontiff becomes totally incapacitated. Even while unconscious during surgery, Pope Leo remains pope and retains his authority.Pope Francis remained in charge throughout his lengthy hospitalisations, as did St John Paul II before him. Both made appointments and issued laws and statements from the hospital.Medical advances and popes’ longer lifespans, however, have highlighted this gap in church law and prompted calls for the Vatican to prepare for a pope becoming too ill or incapacitated to govern.