Purpose: To determine a histopathologic explanation for focal areas of increased opacity on mammograms of ductal carcinoma in situ of the comedo type (comedocarcinoma).
Materials and methods: From January 1991 to January 1993, mammograms from 36 patients with comedocarcinomas were reviewed. Each mammogram was screened for microcalcifications and/or any focal area of increased opacity. The presence or absence of infiltrating components was confirmed at pathologic examination, with particular emphasis placed on the search for any stromal reaction.
Results: The clinical examination revealed a palpable tumor in five patients (14%) and a bloody discharge from the nipple in two (5%). Isolated clusters of microcalcifications were seen at mammography in 24 patients (67%). Nine patients (25%) had clusters associated with focal areas of increased opacity; three patients (8%) had no microcalcifications. Histologic analysis demonstrated an intense, periductal, inflammatory reaction in all 12 patients with focal areas of increased opacity.
Conclusion: Focal areas of increased opacity are not always indicative of an infiltrating component and may merely represent intense stromal reaction.