Lobular neoplasia (LN) and columnar cell alterations (CCAs) may share similar genetic abnormalities, but there is no appreciable literature that addresses the simultaneous occurrence of these lesions in breast core biopsy (CNB) specimens or resection specimens. Three groups of breast tissue were examined: group 1, 68 CNB specimens targeted for "suspicious" microcalcifications (Breast Imaging Reporting and Data System [BI-RADS] 4) and diagnosed with LN; group 2, 2,516 CNB reports for a 1-year period; and group 3, 400 consecutive breast carcinoma resection specimens analyzed for LN and CCAs within the vicinity of carcinoma. In group 1, LN was associated with CCAs in 54% of cases (37/68). In group 2, LN was found in association with CCA in 1.3% of cases (32/2,516). In group 3, 13.0% of cases of CCAs (52/400) were associated with LN. Our study suggests the association of these two lesions in breast tissue is nonrandom and that they may have a common progenitor pathway of neoplastic development.