Mucinous Breast Carcinoma Presenting as a Coarse and Densely Calcified Mass on Mammography: A Case Report.

We report herein a 46-year-old woman who presented with mucinous breast carcinoma that appeared as a coarse and densely calcified mass on mammography. The lesion was a 4.6-cmsized palpable, hyperechoic, calcified mass with posterior shadowing on ultrasonography. This finding is a unique feature of mucinous breast carcinoma and is also observed in unusual breast cancer variants such as metaplastic breast cancer with chondroid differentiation, extraosseous osteosarcoma, and breast chondrosarcoma. The lesion showed a slow-growing pattern throughout the 4-year observation period. Mammography performed 4 years ago revealed faint, grouped microcalcifications; the lesion increased in size over 2 years, presenting as a well-circumscribed, calcified mass, mimicking dystrophic calcification. As several unusual variants of breast cancer, including mucinous carcinoma, may present as coarse and densely calcified masses on mammography, immediate biopsy should be considered when they are observed.