Metastatic disease of the skeleton.

Metastatic cancer is among the most frequent causes of skeletal pain associated with a destructive bone lesion or pathologic fracture in adults. Patients with a known primary carcinoma should undergo systematic evaluation and monitoring to determine the extent of skeletal disease and risk of pathologic fracture. Patients without a known primary carcinoma who have symptoms consistent with metastatic disease of the skeleton present a diagnostic dilemma. Plain radiographs may not reveal a metastatic lesion until extensive marrow replacement has occurred. Bone scans are more sensitive than radiographs and provide a survey of the entire skeleton. However, increased uptake on a bone scan is not specific and some neoplasms are poorly detected by scintigraphy. Computed tomography can identify bone destruction or neoplastic bone formation that is not easily demonstrated by plain radiographs and can help the clinician assess the risk of pathologic fracture. Magnetic resonance imaging may be helpful in detecting and defining the extent and precise location of marrow lesions and soft tissue extension of neoplasms.