[Paget's disease of the skeleton]

Paget's disease of bone is now regarded as a slow virus disease of the skeleton presenting with localized manifestation. The affected areas show increased turnover with irregular structure (mosaic pattern in histology). The bones are thickened but have decreased mechanical strength. The disease most frequently affects the pelvis, femora, and tibiae, followed by the calvarium, the lumbar vertebrae and others. Diagnosis is made by X-ray examination. The differential diagnosis is rarely so difficult that a bone biopsy is required. Bone scintigraphy reveals asymptomatic lesions. Alkaline serum phosphatase mirrors the activity of the disease. Indications for treatment are pains, bending, deformities, fractures, skull base involvement, nerve damage and very high alkaline phosphatase. Calcitonins and bisphosphonates are used for treatment. Single-agent therapy reduces alkaline phosphatase to 50% of the initial level. If more intensive treatment is desired, a combination of calcitonin and EHDP can be used. Paget's sarcoma develops in less than 1% of patients with Paget's disease of bone; it is uncertain whether this complication can be prevented or delayed by the therapeutic regimens currently in use.