Dealing with a soft tissue lesion that is scheduled for CT-guided biopsy and that has decreased in size on preprocedural planning CT.

On planning CT before CT-guided biopsy, the target lesion may have decreased in size compared to previous imaging. Radiologists frequently face the dilemma of whether to biopsy these shrinking lesions or not. There is currently a lack of literature on how often such a situation is encountered in clinical practice, how it is dealt with, and if the perceived lesion size reduction always implies benignancy. This information would be valuable to develop evidence-based strategies for this specific clinical situation. We aimed to determine the frequency, radiologist's management, and nature of lesions with size reduction on prebiopsy planning CT. In this retrospective study, we found that the incidence of lesions with size reduction on prebiopsy planning CT was 1.00% (11/1103). Biopsy was refrained from in most cases (9/11). Eight lesions proved to be benign, one malignant, one harboured both benign and malignant pathology, and one lesion remained of unclear nature. Soft tissue lesions with size reduction on prebiopsy planning CT are encountered infrequently and are usually not biopsied. Although most of these lesions are benign, lesion size reduction does not exclude malignancy. Therefore, clinical and imaging follow-up should be considered mandatory when biopsy is cancelled.