Objective: The purpose of our study was to determine the proportion of bone lesions with indeterminate results after initial percutaneous CT-guided bone biopsy that ultimately are found to be malignant and whether CT features are associated with diagnostic outcomes.
Materials and methods: The results of 800 consecutive percutaneous CT-guided bone biopsies performed at a tertiary cancer center were reviewed. The initial histopathologic diagnosis was classified as diagnostic or indeterminate. On the basis of follow-up information, indeterminate results were subcategorized as benign, malignant, or persistently indeterminate. Two readers independently analyzed the CT images.
Results: Initial percutaneous CT-guided bone biopsy was diagnostic in 69% and indeterminate in 31%. Malignancy was diagnosed in 90% of initially diagnostic results. In lesions with initially indeterminate results, a diagnosis was subsequently made in 62%; 39% of subsequent diagnoses were malignant as of the last available follow-up. CT features associated with diagnostic results included cortical destruction and large extraosseous mass (p < 0.05). More lesional sclerosis and presence of fat were associated with indeterminate results (p < 0.001). CT features associated with malignant results included less-extensive sclerosis and lesser sclerotic rim (p < 0.05). Increased age, female sex, and a cancer history were associated with higher risk of malignancy among patients with diagnostic results at initial biopsy.
Conclusion: Bone lesions that initially yield indeterminate results at percutaneous CT-guided bone biopsy often are subsequently shown to be malignant; vigorous pursuit of a diagnosis is recommended if initial results are indeterminate. Lesions showing fat or more sclerosis are more likely to be indeterminate; lesions with less sclerosis or smaller sclerotic rim are more likely to yield malignant results.