The use of stereotaxic core biopsy and stereotaxic aspiration biopsy as diagnostic tools in the evaluation of mammary calcification

We compared stereotaxic fine needle aspiration biopsy (SFNA) with stereotaxic core needle biopsy (SCB) in the evaluation of radiographically clustered mammary microcalcification, a common finding at screening mammography. Over a 4-year period, 181 specimens were obtained from 175 patients who underwent both SFNA and SCB of clustered microcalcification. Aspiration and core biopsies were performed by radiologists at a community-based diagnostic radiology facility. All aspiration smears were air dried, stained on site, and assessed for adequacy by the radiologists, then sent to the cytopathologists at New York University for interpretation. Core biopsy specimens were formalin fixed, paraffin embedded, hematoxylin and eosin stained, and interpreted by surgical pathologists at a community hospital. Of 181 SFNA specimens, 133 (74%) were benign, 18 (10%) were atypical, 13 (7%) were suspicious, and 16 (9%) were malignant. One (0.5%) aspiration biopsy was nondiagnostic. Excisional biopsies were performed after 12 benign SFNAs and in 46 of the 47 cases with an atypical, suspicious, or malignant diagnosis on SFNA. Mammographic follow-up in 111 of the 133 cases (92%) diagnosed as benign showed no radiologic change (mean 29.2 months, range 6-60 months). The false-negative rate for cancer was 4% (6 cases) for SFNA alone. There were no false-positive diagnoses for SFNA. There was one false-positive diagnosis on core biopsy [focal cribriform ductal carcinoma in situ (DCIS)], which at excisional biopsy and correlation with the core biopsy was diagnosed as ductal hyperplasia; the false-negative rate for cancer was 8% (13 cases) for SCB alone. Aspiration biopsy identified calcification in 180 procedures, core needle biopsy revealed calcification in 170. SFNA was superior to SCB for the confirmation of clustered mammary microcalcification (99% versus 94%) and in the identification of cancer associated with microcalcification (false negative rate of 4% versus 8%). Patients with benign findings on stereotaxic aspiration and core biopsy can reasonably be followed mammographically.