Authorities did not immediately say whether the woman found Tuesday at San Francisco General Hospital was Lynne Spalding, 57, a native of England who was being treated for an infection at the hospital when she disappeared from her room on Sept. 21.
Police, coroner and sheriff's officials were investigating the death of the woman found at about 10 a.m. by an employee in the exterior stairwell that is used as a fire exit, hospital spokeswoman Rachael Kagan said.
It's not clear how long the woman was there, or how she got there.
"It's very concerning," Kagan said. "We're distressed and don't know what happened. It's our top priority to find out."
Spalding was last seen two days after she was admitted to the hospital. Friends say she was very thin and frail, was on medication and probably very confused. A missing persons report was filed with police, who have been investigating her disappearance.
David Perry, a spokesman for Spalding's family, said he found the discovery disturbing.
"What is happening here today is very distressing, and although we hope that our friend and our colleague Lynne Spalding will come back to us alive and healthy, we're very concerned about this," Perry said.