Solitary abnormalities in bone scans of patients with extraosseous malignancies.

The incidence and significance of solitary bone scan abnormalities were assessed in a study of 1,129 consecutive patients with extraskeletal primary malignancies. Solitary abnormalities were encountered in 172 cases (15%). The etiology of the scan abnormality was established in 90 of the 172 cases; 58 (64%) were due to metastatic disease, and 32 (36%) were secondary to a benign process. A significant percentage of solitary scan abnormalities is due to benign disease processes, even in patients with proved extraosseous malignancies.