The "black beard" sign of monostotic Paget's disease of the mandible.

Paget's disease of bone can occur in up to 4% of the population over forty. Most of these patients are asymptomatic, and will have more than one bone involved. The monostotic presentation of the disease is much less common, but not rare. Monostotic Paget's disease involving the mandible, however, is very unusual. Only six cases have been reported since 1945, and bone imaging did not play a significant role in the diagnoses of these reports. A patient with proven Paget's disease of the mandible presented with a rather dramatic "bearded" image on a bone scan.