Comparison of mammographic and sonographic findings in typical and atypical medullary carcinomas of the breast

AIM: The aim of this study was to describe the contribution of mammographic and sonographic findings to the discrimination of typical and atypical histopathologic groups of medullary carcinomas of the breast. MATERIALS AND METHODS: Imaging findings were retrospectively assessed in 33 women with medullary carcinomas (15 typical medullary carcinomas and 18 atypical medullary carcinomas) identified during pre-operative mammography. Twenty-nine of these women also had ultrasound and these findings were reviewed. RESULTS: Mammography showed a well circumscribed mass in 10 of the 15 (67%) typical medullary carcinomas and in four of the 17 (24%) atypical medullary carcinomas (P < 0.02). One small tumour in a woman with atypical medullary carcinoma was missed on mammography and was shown only on sonography. Sonographically, an irregular margin surrounding the whole mass or part of it was seen in three out of 14 (21%) patients with typical medullary carcinoma and in nine out of 15 (60%) patients with atypical medullary carcinomas (P < 0.05). Posterior acoustic shadowing was more often observed in the typical medullary carcinoma group than in atypical medullary carcinoma and the difference was found to be statistically significant (P < 0.05). None of the other mammographic and sonographic findings were sufficiently characteristic to allow for a differentiation between two groups. CONCLUSION: When typical medullary carcinomas were compared with atypical medullary carcinomas according to imaging features, they tended to be well circumscribed masses on both mammography and sonography, and a posterior acoustic shadow was not found on sonography. However, the imaging findings in these two subgroups often resembled each other and histopathology will always be required to confirm the diagnosis. (C) 2002 The Royal College of Radiologists.