Although core needle biopsy (CNB) is considered to be the standard technique for histological diagnosis of breast lesions, it is less reliable for diagnosing atypical ductal hyperplasia (ADH). We therefore assessed the characteristics of CNB-diagnosed ADH that are more likely to be associated with more advanced lesions on subsequent surgical excision.

We retrospectively examined 239 consecutive CNBs, 127 of which were diagnosed as ADH following surgical excision, performed at Asan Medical Center between 1995 and 2010. Archival slides were analyzed for the number of cores per specimen, the number of ADH foci, and the ratio of ADH foci to number of cores (FC ratio).

We found that ADH foci in 3 or more cores (p=0.003) and the presence of ADH in 3 or more foci (p=0.002) were correlated with malignancy following excision lesion. Moreover, an FC>1.1 was significantly associated with malignancy in the subsequent excision (p=0.000).

Including the number of ADH foci, the number of cores involved according to ADH, FC ratio, and histologic type in a pathology report of CNB may help in making clinical decisions about surgical excision.