Bilateral breast carcinomas: Do they have similar mammographic features?

AIMS: This study compared the mammographic appearance, site and histologica l features of synchronous and metachronous bilateral breast carcinomas. METHODS: Site, type of abnormality and background pattern seen on the diagn ostic mammograms of 63 women with bilateral breast carcinoma were compared, The histological type and grade of all the carcinomas were verified by his tological review. RESULTS: There was a tendency for the contralateral tumour to have similar mammographic features to those of the initial tumour. In patients in whom t he first carcinoma was visible purely as a mass, the contralateral carcinom a had a similar appearance in 82% (P < 0.001). When the original tumour sho wed mammographic calcification the contralateral tumour did so in 65% (P < 0.001). Normal mammography or calcification alone were seen almost exclusiv ely in women with a dense background pattern (100% and 92% respectively) wh ile 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 tren d for contralateral carcinomas to be of the same histological grade (P < 0. 005) but not histological type. CONCLUSIONS: Contralateral carcinomas often have a similar mammographic app earance to the first tumours. Two factors may be responsible: (i) the tende ncy for contralateral carcinomas to be of the same histological grade and ( ii) the influence of mammographic background pattern on the radiological ap pearance of breast carcinoma. This knowledge may assist in the interpretati on of follow-up mammography in patients with a previous breast carcinoma.