Objective: We sought to assess the probability that a new suspicious bone lesion is an alternative diagnosis, that is, a benign lesion or a second malignant tumor as opposed to metastatic disease from the malignant tumor, in a person with known primary malignant disease.
Materials and methods: We reviewed the radiologic and pathologic records of bone biopsies scheduled at our institution between 2002 and 2007. The following parameters were recorded: indication, type of primary cancer, date of diagnosis, complications of biopsy, whether the sample was of diagnostic quality, pathologic finding, and thus whether the primary malignant tumor was concordant with the lesion sampled.
Results: Fifty-four of 55 patients (17 men, 37 women; mean age, 67 years) with known primary cancer and suspicious bone lesions underwent biopsy. One of the 55 patients did not undergo biopsy because a sacral insufficiency fracture was confidently diagnosed at CT. The primary malignant disease had been diagnosed up to 16 years before the new bone lesion was suspected and bone biopsy performed. Cancer types included those of genitourinary tract, breast, thyroid, gastrointestinal tract, and lung and lymphoma and myeloma. Diagnostic material was obtained in 43 of 54 cases (80%), and nondiagnostic material was obtained in 11 of 54 cases (20%). Forty-two of 43 positive biopsy findings (98%) were consistent with the primary malignant tumor. The other positive finding was a new malignant tumor. This new tumor was myelofibrosis in a man with chronic myelocytic leukemia. The primary diagnosis correlated highly with that of the new bone lesion (Spearman's test, R = 0.842; p < 0.001). No complications, including hemorrhage, infection, sinus track formation, fracture, and pneumothorax, were encountered.
Conclusion: In a patient with known primary malignant disease, the probability is low (2%) that biopsy of a new suspicious bone lesion will show the lesion is other than metastasis from the primary tumor.