The literature shows a wide range in the frequencies of finding breast carcinoma in the excised specimens following a biopsy diagnosis of atypical ductal hyperplasia (ADH), likely due to a poor diagnostic reproducibility among different pathologists as well as an inherent heterogeneity in ADH. We evaluated whether histologic subtyping of ADH would help predict the risk of breast carcinoma. Our study consisted of 143 cases of ADH diagnosed by core needle biopsy and followed by excision. Of these, 54 cases (37.8%) showed carcinoma in the excised specimens (47 cases of ductal carcinoma in situ alone, 3 cases of invasive ductal carcinoma alone, and 4 cases of mixed invasive ductal carcinoma and ductal carcinoma in situ). We arbitrarily divided ADH into two subtypes: type A was considered when one or more ducts were completely replaced by low-grade ductal carcinoma in situ type cells but the lesion was <2 mm and type B was considered when one or more ducts were partially involved by low-grade ductal carcinoma in situ type cells regardless of lesion size. Type A was associated with a significantly higher frequency of breast carcinoma (63.6%) than type B (30.0%). ADH containing punctate necrosis showed a higher association of carcinoma (66.7%) compared to those without necrosis (35.1%). Within type B ADH, involvement of 3 or more foci had a higher frequency of carcinoma (50.0%) than involvement of fewer foci (26.6%). These histologic features of ADH may prove useful in predicting the likelihood of breast carcinoma and provide helpful information for patient's management.
Keywords: atypical ductal hyperplasia; breast carcinoma; core needle biopsy; predict the likelihood; routine histologic features.