Adequate Core Biopsy Samples from Stereotactic Biopsies Needed for Today’s Breast Pathology

Background: There is a paradigm shift in breast biopsy philosophy. In the past radiologists and clinicians used to collect as little tissue as possible for pathologists to render a diagnosis on conventional histologic H&E sections. Precision medicine has changed this philosophy in such a way that more optimal core biopsy specimens are now required to provide more data for personalizing the therapy. Methods: Two cases are presented in this study to illustrate the importance of adequate stereotactic breast biopsy samples. In each case digital mammography revealed grouped heterogeneous calcifications in a postmenopausal woman. A core biopsy was performed using stereotactic 8 gauge vacuum-assisted biopsy equipment. Cores were collected in touch-free collection chambers; and the specimen radiograph confirmed the targeted calcifications. Core biopsy samples were completely submitted for paraffin embedding into two cassettes. Cores bearing microcalcifications on specimen radiography were submitted for paraffin embedding in one cassette; the remainder cores were submitted in another cassette. Results: In one case, microscopic examination revealed ductal carcinoma in situ grade 1 (DCIS grade 1) measuring more than 2 mm in linear extent involving multiple ducts on a single core with microcalcifications. In another case, microscopic examination revealed ductal carcinoma in situ grade 2 with microcalcifications (DCIS grade 2) mixed with moderately-differentiated invasive ductal carcinoma. P63 and calponin immunostains delineated the size of invasive carcinoma (2.5 mm, pT1a) and DCIS (> 6 mm) on a single core. Conclusions: An important diagnostic criterion for classification of low nuclear grade atypical ductal proliferations is the size/extent of the lesion. Larger, intact, unfragmented biopsy samples enable atypical ductal hyperplasia (ADH) versus DCIS grade 1 distinction possible as seen in first case. The distinction between these two diagnoses often mean a difference in how the patient proceeds with treatment, reinforcing the need to acquire high quality and quantity of biopsy samples. Adequate, unfragmented samples provide high quality tissue for accurate diagnosis and further ancillary studies as seen in the second case. Author details 1 Clinician, Department of Pathology, Yale University School of Medicine, Yale New Haven Hospital, 20 York Street EP2, Room 631A New Haven, Connecticut (06504) U.S.A.