Background: The surgical management of lobular in-situ neoplasia (LN) identified by core needle biopsy (CNB) is currently variable. Our institution has routinely excised LN on CNB since 2003, allowing for an unbiased assessment of upgrade rates.
Methods: Cases of LN on CNB, including atypical lobular hyperplasia (ALH) and lobular carcinoma-in-situ (LCIS), were identified in our pathology database. CNBs with concurrent pleomorphic LCIS, ductal carcinoma-in-situ (DCIS), and invasive carcinoma were excluded. Imaging indication/modality, biopsy indication, and radiologic concordance were determined. Pathology review included scoring total foci of LN in each CNB. Upgrade rates to invasive carcinoma or DCIS at excision were calculated.
Results: A total of 106 cases of LN (73 ALH and 33 LCIS) on CNB were identified. Thirty patients had concurrent atypical ductal hyperplasia (ADH) and 76 had LN alone; 93 (88%) of the patients had available surgical follow-up (25 LN + ADH and 68 LN alone). The upgrade rate at excision was 16% (4 of 25) for LN + ADH and 4.4% (3 of 68) for LN alone. Patients with LN alone and discordant imaging, imaging for high-risk indications, or extensive LCIS (>4 foci) accounted for all the upgrades. Normal-risk patients who underwent biopsy to assess calcifications found by routine mammographic screening with LN alone did not result in upgrade.
Conclusions: Women with a CNB diagnosis of LN for calcifications found on routine, normal-risk mammographic screening have a negligible risk of upgrade and may not require excisional biopsy. However, excisional biopsy should be offered to women undergoing imaging for other indications or with >4 foci of LN on CNB.