Dear Dr. Roach: My dentist saw a large mass on my jaw and sent me to an oral surgeon, who said the mass was too large. He sent me to a maxillo-facial surgeon, who did a scan and biopsy. I was diagnosed with Paget’s disease but the surgeon had never seen a case before and sent me to a rheumatologist. That doctor sent me for a blood test and a full body scan, which found that it is also on my spine. The rheumatologist couldn’t give me much information either. I am hoping that you can tell me what this is and what any treatment or long-term side effects are. — D.S.

Answer: Paget’s disease of bone is a disorder of bone metabolism. It happens usually in people over 55, and the diagnosis is often made by incidental finding of abnormal blood tests, especially the alkaline phosphatase. It may also be found when a painful bone lesion is X-rayed, and as in your case, people often have several other areas that are usually not symptomatic. Paget’s disease is very common, affecting 2% to 9% of older adults, but it is frequently not diagnosed. Examples of this bone disease can be found in ancient history, potentially back to the time of the Neanderthals. Paget’s disease can be found in any of your 206 bones, but the skull and spine are the most common sites. The underlying cause is unknown.

Not everyone with Paget’s disease needs to be treated. People with symptoms due to Paget’s should be treated, as well as people without symptoms but who have “active” disease (as measured by blood tests). People with disease in a critical location may benefit from treatment. The first-line treatment is similar to that for osteoporosis, with medicines like alendronate (Fosamax) or zoledronic acid (Reclast or Zometa).

Without treatment, Paget’s disease tends to progress, so the mass in your jaw would be expected to become larger and could cause mechanical problems, put pressure on an important structure (such as a nerve) or even fracture. While unproven, most experts believe treatment reduces long term