Metaplastic breast cancer mimicking a benign finding on mammography: a case report and literature review

Abstract

Metaplastic breast carcinoma (MBC) may present nonspecific imaging findings that mimic benignity. This case report describes a 77-year-old woman with MBC who initially presented with dystrophic calcification on mammography. A screening mammogram and US examination performed in 2020 showed dystrophic calcification in the left breast, BI-RADS 2. In 2021, screening mammography and US showed the previously detected dystrophic calcification with an increase in size compared to previous examinations, BI-RADS Category 2. Eight months later, she had a rapidly growing mass in the left breast. Mammography and US examination showed a mass abutting into the dystrophic calcification with suspected malignancy, BI-RADS 4B. An excisional biopsy was histopathologically diagnosed as MBC with malignant bone formation and chondroid components. Neoplastic cells were positive for P53 and CK AE1/AE3. Estrogen, progesterone, and HER2/neu receptors were negative. This case report is the first in the literature on MBC initially presenting as dystrophic calcification mimicking benignity. It is published for educational purposes to show mammographic and US findings.