Risk Factors for Diagnostic Failure of Ultrasound-Guided Core Needle Biopsy of Soft-Tissue Tumors Based on World Health Organization Classification Category and Biologic Potential.

OBJECTIVE. The purpose of this study is to evaluate the diagnostic outcome of ultrasound (US)-guided core needle biopsy (CNB) of soft-tissue tumors and to assess the factors associated with significant diagnostic failure. MATERIALS AND METHODS. We performed a retrospective analysis of biopsy specimens obtained from patients with soft-tissue tumors of the extremities and superficial trunk who underwent both US-guided CNB and surgical resection. In accordance with the World Health Organization classification, biopsy results and findings from final histologic analysis of the surgically resected specimen (hereafter known as final histologic findings) were categorized in terms of biologic potential as benign, intermediate (locally aggressive), intermediate (rarely metastasizing), or malignant. Biopsy results were considered to show a significant diagnostic failure if they resulted in incorrect classification of biologic potential compared with final histologic findings, if results were indeterminate, or if nondiagnostic specimens were obtained. World Health Organization classification categories and the biologic potential of the tumors according to final histologic findings were assessed to identify any relationship with diagnostic failure of CNB, as were other tumor- and patient-related factors. RESULTS. Significant diagnostic failure was seen for 40 of 303 biopsies (13.20%). Multivariate analysis showed a significant association between diagnostic failure and adipocytic tumors (odds ratio [OR], 9.686; p = 0.037) or vascular tumors (OR, 40.115; p = 0.005); intermediate (rarely metastasizing) biologic potential (OR, 12.279; p = 0.001), or malignant biologic potential (OR, 5.668; p < 0.001); and discordance between radiologic and final histologic findings or indeterminacy of biologic potential (OR, 2.500; p = 0.034). CONCLUSION. The World Health Organization classification categories (adipocytic or vascular), biologic potential (intermediate [rarely metastasizing] or malignant), and discordance between radiologic and final histologic findings or indeterminacy of biologic potential were found to be independent risk factors for significant diagnostic failure of CNB of soft-tissue tumors.