Indeterminate breast fine-needle aspiration: repeat aspiration or core needle biopsy?

Fine-needle aspiration (FNA) of breast lesions provides indeterminate (C1, C3, and C4) diagnoses in a high proportion of cases. The aim of the present study was to retrospectively determine whether repeat FNA or core needle biopsy (CNB) most frequently provides a correct and more conclusive diagnosis. All patients who had an indeterminate primary FNA followed by repeat FNA or CNB within 1 month from 1992 to 2007 were included. FNA was diagnosed as C1-C5; CNB was diagnosed as B1-B5. Improvement in preoperative diagnosis by repeat FNA or CNB was defined as C2/B2 in benign lesions, C3/B3 in premalignant lesions, C4/B4 or C5/B5 in malignant lesions where primary FNA was C1, and C5/B5 in malignant lesions where primary FNA was C3 or C4. Among 255 eligible cases, CNB improved the preoperative diagnosis more often than did repeat FNA (78.0% vs. 54.8%, odds ratio = 2.9, P < .001). When corrected for patient age, appearance on mammogram (mass or not), clinical findings (palpable or not), tumor size, and aspiration mode (freehand vs. image guided), this difference slightly increased (odds ratio = 3.0, P = .001). CNB should be performed after an indeterminate FNA of a breast lesion to obtain a reliable and clear preoperative diagnosis.