Bilateral breast carcinomas: do they have similar mammographic features?

This study compared the mammographic appearance, site and histological features of synchronous and metachronous bilateral breast carcinomas.

Site, type of abnormality and background pattern seen on the diagnostic mammograms of 63 women with bilateral breast carcinoma were compared. The histological type and grade of all the carcinomas were verified by histological review.

There was a tendency for the contralateral tumour to have similar mammographic features to those of the initial tumour. In patients in whom the first carcinoma was visible purely as a mass, the contralateral carcinoma had a similar appearance in 82% (P < 0.001). When the original tumour showed mammographic calcification the contralateral tumour did so in 65% (P< 0.001). Normal mammography or calcification alone were seen almost exclusively in women with a dense background pattern (100% and 92% respectively) while masses and calcification with masses were seen in women with dense and fatty patterns (58% and 35% dense respectively). When the mammographic site of the contralateral tumour was compared with that of the first tumour no significant correlation could be demonstrated. There was a significant trend for contralateral carcinomas to be of the same histological grade (P < 0.005) but not histological type.

Contralateral carcinomas often have a similar mammographic appearance to the first tumours. Two factors may be responsible: (i) the tendency for contralateral carcinomas to be of the same histological grade and (ii) the influence of mammographic background pattern on the radiological appearance of breast carcinoma. This knowledge may assist in the interpretation of follow-up mammography in patients with a previous breast carcinoma.