Background: The increased prevalence of ductal carcinoma in situ (DCIS) has produced a growing awareness of the importance of its diverse patterns. These differences in pattern have become clinically significant as predictive indicators of success for planned local excisions of small DCIS lesions.
Methods: The authors reviewed 100 sequentially collected DCIS cases from a consultation practice. Recognizing the bias of such a series toward exclusion of easily recognizable comedo DCIS, the authors investigated the spectrum of mixed pattern lesions to identify variations and common features in the architectural arrangement of the various histologic patterns.
Results: Patterns of atypical ductal hyperplasia (ADH) with specific criteria of recognition were intermixed in 17 cases (11 cribriform, 1 solid, 1 micropapillary, 4 mixed). Thirty-three cases of DCIS consisted of mixed patterns of comedo and noncomedo types. No case of comedo DCIS with associated areas of ADH was identified. In all cases of combined DCIS and ADH, the more advanced patterns of DCIS were present in the central portion of the lesion, with the ADH components arranged peripherally. This tendency for the more severely atypical areas to be located centrally was present throughout the study.
Conclusions: Different patterns of DCIS are frequently present within individual lesions (46 of 100), and the more advanced features of architectural atypia are regularly present centrally. This strongly supports the hypothesis that these lesions develop from a central focus and expand peripherally. Also, those lesions with low-grade DCIS at the periphery may be as amenable to local excision for cure as purely low-grade lesions.