US-guided core-needle biopsy of the breast: how many specimens are necessary?

To analyze the diagnostic yield for each specimen obtained at 14-gauge ultrasonography (US)-guided breast biopsy and compare these findings with mass, procedural, and specimen characteristics that could affect yield.

Seventy-three consecutive biopsies of breast masses were performed by using a 14-gauge handheld biopsy device. Each specimen was graded for whether it was nonfragmented or fragmented and for whether it sank or floated, and each pass was graded for whether or not the needle passed through the lesion. Each specimen was mounted on a separate slide. A pathologist who was unaware of the final diagnoses reviewed the slides in random order. A diagnosis was determined for each specimen whenever possible, and diagnostic yield was calculated as a function of number of passes. The Fisher exact test was used to compare yield for different specimen characteristics.

Fourteen (19%) lesions were malignant and 59 (81%) were benign. Cells indicating the final diagnosis were contained in 249 (75%) of 334 specimens. Cells indicating the diagnosis were contained in the first specimen in 51 (70%) lesions, in the second specimen in 67 (92%), in the third specimen in 70 (96%), and in the fourth specimen in 73 (100%). Of the 14 malignancies, 13 (93%) were diagnosed with cells contained in the first or second specimen; one cancer (ductal carcinoma in situ) was diagnosed with cells contained in the fourth specimen. Specimens that were nonfragmented (P <.001) and sank (P <.001) showed correlation with being diagnostic, but needle visualization within the lesion did not.

A minimum of four specimens, preferably those that are nonfragmented and that sink, should be obtained with 14-gauge US-guided breast biopsy.