Background: Atypical ductal hyperplasia (ADH) is a proliferative lesion of the breast that expresses some features of
carcinoma in situ. This lesion is associated with increased risk of breast cancer. Surgical excision is usually performed in the
patients with ADH diagnosed by core biopsy (CNBx) due to discordance of the diagnosis. However, only small portion of the
patients had carcinoma in situ or invasive carcinoma.
Objective: To identify parameters that can predict the upgrading from ADH on CNBx to malignancy on subsequent surgical excision.
Material and Method: Clinicopathological data of the patients with ADH diagnosed by CNBx who were underwent surgical
excision at Siriraj Hospital from January 2010 to June 2015 was reviewed. Correlations between clinicopathological parameters and histopathologic results of both CNBx and surgical excision were determined by Chi-square statistics.
Results: Total 86 cases were diagnosed as ADH on CNBx then followed by surgical excision. Seventeen (19.8%) patients were
subsequently upgraded to malignancy. Thirteen (15.1%) patients had ductal carcinoma in situ (DCIS) and 4 (4.7%) patients had invasive ductal carcinoma. Univariate analysis revealed that palpable mass, irregular margin of the mass and multifocality were associated with upgrading to malignancy. Multivariate analysis showed that palpable mass was the independent predictor of upgrading to malignancy.
Conclusion: Presentation with palpable mass was an independent factor for upgrading to malignancy and should be an indication for surgical excision of ADH diagnosed by CNBx.

Keywords: Breast cancer, Atypical ductal hyperplasia, Core biopsy