Pope Leo XIV stunned thousands of pilgrims in St. Peter’s Square on Sunday with an unexpected personal announcement.

Doctors have discovered a small nodule in one of his lungs.

And the 71-year-old pontiff will undergo surgery within days to remove it.

Leo revealed the diagnosis himself after delivering the traditional Sunday Angelus prayer on Oct. 11, telling the crowd that the abnormality had been detected during recent medical examinations.

“Doctors found a localized nodule in my lung,” the pope said.

“It was detected at a very early stage and is well localized.”

He said doctors believed surgery was the appropriate course of action and that he had decided to follow their recommendation.

“The operation is already scheduled for the coming days,” Leo added.

“I thank you for your spiritual closeness and entrust myself to your prayers.”

The Vatican has not said that Leo has cancer.

That distinction is important.

A lung nodule is a small abnormal area visible in lung tissue, and such growths can be either benign or malignant.

The Vatican has not disclosed the results of any biopsy or other testing that would determine the exact nature of Leo’s nodule.

Reuters reported that officials have specifically declined to say whether the growth is cancerous.

For now, the known facts are more limited.

The nodule was discovered during a recent examination.

It is described as small and well localized.

Doctors believe it should be surgically removed.

And Leo says it was found at a very early stage.

The operation is expected to take place at Rome’s Agostino Gemelli University Hospital, the medical center traditionally used by popes for major treatment.

According to AP, Leo is expected to remain hospitalized for approximately one week following the procedure.

The announcement marks the first major health issue disclosed publicly during Leo’s papacy.

Born Robert Francis Prevost in Chicago, Leo was elected pope in May 2025 and became the first American to lead the Roman Catholic Church.

At 71, he is relatively young by modern papal standards.

He has also maintained a notably active schedule since his election.

Leo is known to play tennis and swim and has continued an intense program of public audiences, liturgies and international travel.

Until Sunday, there had been no publicly known major health concern involving the pontiff.

The timing of the surgery immediately raised another question.

Will Leo still be able to make his planned November trip to South America?

The pope is scheduled to travel from Nov. 6 through Nov. 17, with stops in Uruguay, Argentina and Peru.

For now, that trip remains on his official schedule.

AP reported that Vatican officials have not announced any change to the itinerary, while the anticipated recovery period following surgery is roughly one week.

Church leaders around the world quickly responded to the announcement with messages of support.

The United States Conference of Catholic Bishops said American bishops were joining Catholics and “all people of good will” in praying for Leo and his medical team.

Italian church leaders issued similar messages.

Italian President Sergio Mattarella also sent the pope his support, while bishops in Uruguay said preparations for Leo’s planned November visit would continue as they prayed for a swift recovery.

The announcement was striking partly because Leo chose to disclose the diagnosis himself.

Rather than issuing the information solely through a Vatican medical bulletin, he addressed it directly before thousands of people gathered below the Apostolic Palace.

His language was calm.

He emphasized that the nodule had been discovered early.

He said doctors considered surgery advisable.

And he immediately asked the faithful for prayers.

Medical specialists quoted by AP cautioned against assuming that a lung nodule automatically means cancer.

Such nodules can result from previous infections, inflammation and other non-cancerous causes.

At the same time, doctors generally investigate suspicious nodules carefully because some can represent early-stage malignancies.

Surgical removal can provide both treatment and the tissue needed for a definitive diagnosis.

Leo’s age makes the discovery significant, but the early identification and localized nature of the growth are potentially encouraging factors.

Further information about prognosis and any additional treatment would depend on what doctors find after the operation.

Until then, speculation about cancer would be premature.

Leo continued with his public duties Sunday after making the announcement.

He also used his remarks to renew his appeal for peace in Ukraine and to draw attention to the war’s effects on global food supplies.

The pope called for the safe transport of Ukrainian grain through the Black Sea, warning that people far beyond the battlefield — especially in poorer countries — continue to suffer from disruptions caused by the conflict.

“The daily life of many people cannot be hostage to war,” he said.

But by the end of the Angelus, attention had inevitably turned toward the pope himself.

A pontiff who has spent much of his first 17 months speaking about war, poverty, migration and human dignity had suddenly shared a deeply personal uncertainty.

Doctors have found something in his lung.

They want it removed.

The operation will happen within days.

What the nodule actually is remains unknown.

For now, Leo’s message was simple.

It was found early.

He is following his doctors’ advice.

And he is asking the world to pray.