Mayor Bob O'Connor, hospitalized Thursday with what were described as flu-like symptoms, has been diagnosed with a duodenal ulcer, his spokesman said last night.

"It is not cancerous. There was no bleeding. It will be treated with medication and a revision of diet and schedule," said spokesman Dick Skrinjar.

The mayor will continue treatment at UPMC Shadyside with his family physician, who has asked that his name not be given to the media.

"He will be released probably late Sunday afternoon, early Sunday evening," Mr. Skrinjar said. "He will most likely relax on Monday at home, and plans to attend the Home Run Derby on Monday night, and plans to attend the All-Star Game on Tuesday night."

As for flu-like symptoms reported by the mayor's office earlier in the day, Mr. Skrinjar said doctors are "just going to give him plenty of fluids, let him rest, and let Mother Nature take its course."

A duodenal ulcer is a lesion or sore in the lining of the duodenum, a tube leading from the stomach that forms the first part of the small intestine.

There was a flurry of activity at the hospital around 2:30 yesterday afternoon. Two top aides -- Dennis Regan, director of intergovernmental relations, and executive secretary Marlene Cassidy -- arrived at the hospital. The mayor's son, the Rev. Terry O'Connor, then left the hospital, saying his father was "OK" and needed more tests.

A moment later, the mayor was wheeled on a gurney, eyes closed, from one part of the hospital's South Pavilion to another. He was accompanied by his personal security detail, Officer Joseph Ryczaj, and about four members of the hospital staff.

Mr. Skrinjar said the mayor had asked questions about city business during the afternoon.

He said Judy O'Connor, the mayor's wife, had been with him on and off throughout the day. He said the city was not naming an acting mayor during Mr. O'Connor's hospitalization, as it must under the Home Rule Charter if the mayor is incapacitated.

Mr. O'Connor, 61, was admitted to the hospital Thursday, complaining of a sore throat and flu-like symptoms. He went to the emergency room because his doctor was out of town.

Mr. O'Connor was up and around and conducting brief interviews into Thursday afternoon. He maintained his usual hectic schedule, even ceremonially installing Downtown's first Wi-Fi antenna in Market Square.

But city hall workers said he was lethargic and raspy behind the scenes. "If he'd have listened to the people he works with, he'd have taken Wednesday and Thursday off," said Mr. Skrinjar.