Core biopsy of the breast with atypical ductal hyperplasia - A probabilistic approach to reporting

The diagnosis of atypical ductal hyperplasia (ADH) at needle core breast bi opsy (NCB) is typically regarded as an indication for surgical excision. Al though ADH is an intermediate risk nonobligate precursor lesion, the ration ale for further therapy is the result of a reported high prevalence of a co ncomitant more advanced lesion (typically ductal carcinoma in situ) as the index lesion. To assess whether certain histopathologic features of ADH in NCB are predictive of open biopsy outcomes, the authors correlated the exte nt and pattern of ADH in 47 core biopsies (11- or 14-gauge) with the subseq uent surgical specimen. Extent of ADH on NCB was ascertained by determining the number of large ducts and/or terminal duct-lobular units affected, wit h involvement of one large duct or one terminal duct-lobular unit represent ing a single focus, involvement of one duct and one terminal duct-lobular u nit as two foci, and so on. Of the 47 cases, ADH was restricted to less tha n or equal to2 foci in 24 cases (51.1%), confined to 3 foci in 8 cases (17. 0%), and involved greater than or equal to4 foci in 15 cases (31.9%). The c orresponding histopathologic findings at excision were benign lesions witho ut atypia (n = 14), focal residual ADH (n = 13), atypical lobular hyperplas ia (n = 3), ductal carcinoma in situ (n = 15), and invasive mammary carcino ma (n = 2). When the number of foci of involvement by ADH on NCB. (based on an average of 11.6 cores per case) was correlated with the open biopsy res ults, all cases of ADH limited to less than or equal to2 foci had no worse lesion on excision, whereas ADH present in greater than or equal to4 foci w as found to be a strong predictor of a more advanced lesion on excision (p <0.0001, <chi>(2)). When histologic pattern was evaluated, all cases of pur e micropapillary ADH on NCB showed pure micropapillary ductal carcinoma in situ on excision.