Granular Cell Tumor of the Breast Diagnosed by Core Needle Biopsy: A Case Report

Granular cell tumor rarely occurs in the breast. We report a 69-year-old woman with a right breast mass that simulated carcinoma on palpation, mammography, and ultrasonography. Aspiration biopsy cytology showed no malignant atypical cells. Core needle biopsy was performed to obtain an accurate diagnosis. The lesion was histologically confirmed to be a granular cell tumor. Immunostaining was positive for S-100 protein and vimentin, and negative for keratin, carcinoembryonicantigen, estrogen receptor and gross cystic disease fluid protein-15. The tumorwas treated by wide local excision. Surgeons should be aware that granular cell tumor can resemble breast cancer in order to avoid performing a needless radical mastectomy.