Objective: To characterize the mammographic appearance of cancerization of lobules by ductal carcinoma in situ (DCIS), by correlating imaging and histological findings. Materials and Methods: This retrospective study was based on a review of the histopathological reports of 135 patients who underwent breast biopsy. A diagnosis of cancerization of lobules by DCIS was confirmed in 12 patients. Two cases were excluded because the histopathological sections were not available to correlate pathological and mammographic findings. All mammograms were retrospectively reviewed and categorized by two experienced breast radiologists, with no knowledge of the histological findings. Results: Nine cases (90%) presented clusters of round microcalcifications, and one (10%) had round and linear calcifications. The distribution of the calcifications was defined as lobular in all the cases. Histopathological study showed four cases of cribriform DCIS, two cases of comedo DCIS, one case of solid DCIS, one case of cribriform associated with solid DCIS, and one case of cribriform associated with solid and comedo DCIS. In the case showing round and linear calcifications, the histological subtype was cribriform DCIS. With respect to the number of microcalcifications, nine cases presented more than 20, and only one case showed less than 10 microcalcifications. Conclusion: In our cohort, the mammographic evaluation of patients with DCIS presenting cancerization of lobules demonstrated clusters of microcalcifications in a lobular distribution. Although clusters of round calcifications are typically associated with a benign process, cancerization of lobules by DCIS may produce a similar pattern, thus mimicking a benign condition.

Keywords: Mammography; Ductal carcinoma in situ; Microcalcifications.