Solitary bone metastases of unknown origin.

Patients with a newly detected solitary bone metastasis and no history of cancer need extensive diagnostic testing. One hundred and twenty biopsy samples of patients with metastatic bone disease were referred to the authors' pathology department between June 2005 and December 2012. Thirty-three (27.5%) of these patients with a solitary metastasis of unknown origin, and without visceral metastases, were studied retrospectively. Most metastases were found in the spine (14/33 or 42.4%), or in the pelvis (7/33 or 21.2%). The lung was the most common primary site, but this is not universal in the literature. A useful flowchart for the clinician, confronted with a bone metastasis from an unknown primary site, is the following, according to the literature: history and physical examination, biochemistry with tumor markers and immunoelectrophoresis, chest radiograph, CT-scan of chest and abdomen, and bone scan.