Ultrasound guided core needle biopsy of soft tissue tumors; a fool proof technique?

To assess technical and lesion related factors affecting the quality of ultrasound guided core needle biopsy (CNB) of musculoskeletal soft tissue tumors.

Data of 223 CNBs were evaluated in a retrospective study. Diagnostic yield was calculated for all lesions on the basis of lesion location (extremity/torso), examiner, biopsy needle gauge/length and number of acquired samples. Diagnostic accuracy was calculated for surgical lesions (n= 113) based on final specimen histology. Chi-square test based Phi-coefficient calculations were performed to search for associations between each factor and diagnostic yield.

Overall diagnostic yield was 94.6%. There was no significant difference in diagnostic yield between specialist biopsies (96.8%) and resident biopsies (93.1%), between lesions located in the extremities (94.9%) and lesions in the torso (93.8%) and on the basis of needle gauge or number of acquired cores. Diagnostic accuracy was 100% for surgical lesions. The only factor influencing the quality of CNB was lesion composition (repeat biopsies in myxoid and/or inhomogeneous lesions).

The most important aspects to achieve constant high quality results with ultrasound guided CNBs in the work-up of musculoskeletal soft tissue tumors are expertise concerning identification and targeting of viable tumor components and strict adherence to a quality controlled biopsy procedure. Once this is achieved, technical factors have almost no effect on the quality of CNB.