While the family of Jorge Mas Canosa talked openly of his affliction with Paget’s disease, the head of the Cuban exile movement died from much more serious ailments: lung cancer, kidney failure and cardiac arrest.

Mas was known to be in poor health _ rumors at times had him close to death _ and many believed the primary affliction was a relatively obscure, but not rare, condition related to bone formation.

Family members told associates and the media that Mas was suffering from Paget’s disease, in which bone is broken down faster than usual and new bone forms so rapidly that its structure becomes jumbled.

The new bone also is softer than usual, and nearby joints can develop arthritis. Moreover, bones can break more easily, the thigh or leg can become bowed, and the spine can curve forward.

“It can create a great deal of pain,” said anesthesiologist Scott Berger of Delray Beach, who has treated several Paget’s disease patients.

Pinched nerves in the spine can cause sciatica, which results in radiating pain from the back into the buttocks and into the legs, Berger said.

“It also can cause hearing loss, enlargement of the skull and cardiac failure, although people usually don’t die from this disease,” said Dr. Elliott Hinkes, a Pompano Beach orthopedic surgeon.

Paget’s disease is slightly more common in men than in women, and often begins after age 50. It can be diagnosed on X-rays, according to The Paget’s Disease Foundation in New York.

The disease, thought to be caused by a virus, affects mostly Caucasians of northwestern European ancestry, and is seen occasionally in African-Americans. No one has proved it is hereditary, although it sometimes runs in families, the foundation said.

“Most people with Paget’s disease have no symptoms. Those who do, experience mild pain,” according to Dr. Frederick Matsen III, chairman of the Department of Orthopaedics at the University of Washington at Seattle.

If left untreated, according to medical literature, Paget’s disease can lead to bone and connective tissue tumors, neurological problems if the spinal cord is involved, congestive heart failure and degenerative joint disease.

Non-steroidal anti-inflammatories and non-narcotic pain relievers are used to reduce pain, and other medications are used to slow the rate of bone breakdown and formation, doctors said.

“We generally don’t look at this as a potentially fatal disease,” Berger said. “But, if the vertebrae and ribs are involved, the pain can result in a diminished ability to cough and clear secretions from the lungs. That could lead to serious problems.”