Insufficiency fractures of the pelvis that simulate metastatic disease.

Insufficiency fractures of the pelvis, which almost always occur in elderly women with osteoporosis, are often misinterpreted as metastatic disease. The initial symptom of such fractures is severe pain unassociated with an obvious history of trauma. The typical sites of involvement are the sacrum, the iliac bones, and the pubis. The plain film appearance of the sacral and iliac fractures is usually subtle and easily overlooked, and bone scans will show the abnormal areas more readily. The existence of multiple fractures not only in the pelvis but also in the vertebrae and ribs should suggest the diagnosis of insufficiency-type stress fractures. Computed tomography can exclude the presence of a destructive process and an associated soft tissue mass, as would be seen in metastatic disease. If insufficiency fractures are identified in the typical anatomic locations, bone biopsy is unnecessary.