Medullary carcinoma of the breast: mammographic and US appearance.

Medullary carcinoma of the breast is an uncommon tumor, which may mimic a benign mass at both mammography and ultrasonography (US). A total of 24 medullary carcinomas visible at mammography appeared as round or oval, noncalcified masses with varying degrees of marginal lobulation. In six of the 24 patients, US demonstrated well-defined masses with an inhomogeneous, hypoechoic texture. There was no attenuation of sound, and all lesions showed enhanced through transmission.