Mammographic features of ductal carcinoma in situ (DCIS) present on previous mammography.

AIM: To review previous mammograms of women found later to have DCIS and identify features which may have been missed or misinterpreted as benign. METHODS: The previous mammograms of 50 women who developed DCIS were analysed. The mammographic features at diagnosis and on the prior mammograms were compared. RESULTS: 11 (22%) of the previous mammograms were in retrospect abnormal; 5 (45%) of these had previously been assessed for the abnormality. All showed microcalcification. The following features were commoner at diagnosis than on previous films; rod shaped calcification (64 vs. 27%, P = 0.03) and a ductal distribution of calcification (76 vs. 45%, P = 0.05). Predominantly punctate calcification (64 vs. 12%, P = 0.001) and less than 10 calcifications in the cluster (54 vs. 24%, P = 0.05) were more common on the previous films. No difference was found in the frequency of granular calcification, branching calcification, irregularity in density, size or shape of calcification between the two groups. CONCLUSION: Features of DCIS missed on previous mammography include small cluster size, less than 10 calcifications in the cluster, the absence of rod shaped calcifications, the absence of a ductal distribution and the presence of predominantly punctate calcification. Features frequently seen both at diagnosis and on previous films which might have allowed earlier diagnosis were granular calcifications which vary in size, density and shape in an irregularly shaped cluster. Focal clustered calcification deserves aggressive investigation.