Snap Shot A 68-year-old female immigrant from Mexico presents with a massively enlarged left breast. A fine needle aspiration was performed and the cytology came back as negative. Therefore an incisional biopsy was performed which showed the following histology. Introduction The most common malignant stromal tumor of the breast a mesenchymal tumor arrising from breast lobular tissue the stroma is hypercellular, but the epithelial layers are benign Most are benign (therefore sarcoma is a misnomer) only 10% are malignant Average age is > 30 years of age Rarely metastasizes to the axillary nodes Presentation Presents as a mobile smooth breast mass Produces massive breast enlargement Evaluation Resembles a fibroadenoama on mammogram Diagnosed with a biopsy fine needle aspiration (FNA) for cytologic examination usually is inadequate for diagnosis open excisional breast biopsy is the definitive method to diagnose this lesion Treatment If benign treat with wide local excision Axillary disection is only required if palbable nodes present If malignant treat with simple total mastectomy