Pope Leo diagnosed with lung cancer

Pope Leo has been diagnosed with lung cancer, the Vatican said Tuesday.

Why it matters: The Vatican disclosed the pontiff's health news just hours after he underwent surgery to remove the lower lobe of his right lung .

What they're saying: "The surgery was completed successfully, within the expected timeframe and as planned, and the holy father has returned to his room," per a Holy See Press Office statement published Tuesday.

The office said in that statement it would provide more information shortly, and later followed up with news of Leo's diagnosis of lung adenocarcinoma, which they said tests "conducted beforehand" had led them to suspect.

Driving the news: The first American pontiff was admitted to Rome's Agostino Gemelli University Hospital on Tuesday afternoon for surgery.

"The Pope was in the operating room approximately three hours, while the operation itself lasted about 90 minutes.

The doctors said it was successful and there were no complications," the statement said.

The Catholic Church leader carried out his usual duties Monday and was greeted by supporters and patients at the hospital, according to the Vatican statement.

Zoom in: Adenocarcinoma is the most common subtype of lung cancer, per the Cancer Center.

It forms when the cells lining the outside of the lungs become cancerous.

Its symptoms include persistent cough, shortness of breath and chest pain, amongst other things.

Patients with adenocarcinoma don't always experience symptoms early on, and it is often detected during a scan for a medical reason unrelated to lung cancer.

The big picture: Doctors discovered the nodule during routine medical checkups.

Leo said Sunday that the nodule "was detected at a very early stage and is well localized." He thanked his supporters for their "spiritual closeness" and said he was entrusting himself to their prayers.