Standardized recommendations for the management of lobular neoplasia in core biopsy specimens are not established. The aim of our study was to define morphologic features of lobular neoplasia in core biopsies that predict the finding of ductal carcinoma in situ or invasive carcinoma in the subsequent excisional specimen. We reviewed 333 cases of atypical lobular hyperplasia or lobular carcinoma in situ without ductal carcinoma in situ or invasive carcinoma diagnosed in core biopsies from 1996 to 2006. Subsequent excision was performed in 41% (136/333) of cases, including atypical lobular hyperplasia (n=48), lobular carcinoma in situ (n=39), and lobular neoplasia associated with atypical ductal hyperplasia (n=49). Upgrades were identified in 2% (1/48) of atypical lobular hyperplasia, 23% (9/39) of lobular carcinoma in situ, and 27% (13/49) of lobular neoplasia associated with atypical ductal hyperplasia cases. When further analyzed, the upgraded cases of lobular carcinoma in situ were associated with radiologic-pathologic discordance in 6/9 cases and with nonclassic pathology (two lobular carcinoma in situ with necrosis and one pleomorphic lobular carcinoma in situ) in the remaining three cases. The frequency of upgrade was 11% (3/26) in classic lobular carcinoma in situ, and 46% (6/13) in nonclassic types (pleomorphic or with necrosis). After excluding cases with discordant imaging/pathology, there was a 5% upgrade in our excisional specimens. After excluding cases where the upgrade was associated with nonclassic morphology, the upgrade in our study was 1%. Our results suggest that atypical lobular hyperplasia and classic lobular carcinoma in situ with concordant radiology and pathology can be appropriately managed with clinical follow-up without surgery.