Benign core biopsy of probably benign breast lesions 2 cm or larger: correlation with excisional biopsy and long-term follow-up

PURPOSE To evaluate the accuracy of benign core biopsy of probably benign breast lesions (category 3) 2 cm or larger on the basis of excisional biopsy and long-term follow-up. METHODS We retrospectively reviewed 146 category 3 lesions in 146 patients 2 cm or larger which were diagnosed as benign by ultrasound (US)-guided core biopsy. Patients were initially diagnosed as benign at core needle biopsy and then followed up with excisional biopsy (surgical excision, n=91; US-guided vacuum assisted excision, n=35) or breast ultrasonography (n=20). RESULTS Of the 126 patients who underwent surgical excision or US-guided vacuum-assisted excision, 114 patients were diagnosed with benign lesions, 10 patients with borderline lesions (benign phyllodes tumor), and two patients with malignant phyllodes tumors. The probabilities of lesions being benign, borderline and malignant were 91.8% (134/146), 6.8% (10/146), and 1.4% (2/146), respectively. Of 13 patients who had growing masses on follow-up ultrasonography, three (23.1%) were non-benign (two benign phyllodes tumors and one malignant phyllodes tumor). CONCLUSION US-guided core needle biopsy of probably benign breast mass 2 cm or larger was accurate (98.6%) enough to rule out malignancy. But, it was difficult to rule out borderline lesions even when they were diagnosed as benign.