Clinical history: This 34-year-old woman discovered a palpable breast mass in her left breast. Ultrasound demonstrated a suspicious hypoechoic mass at the 11 o'clock position. A core-needle biopsy was performed and showed dense fibrous tissue only. A follow-up MRI of the breast showed an area of abnormal, non-masslike enhancement, measuring 4.6 x 3.8 x 3 cm. A vacuum-assisted core needle biopsy was performed and showed benign sclerotic mammary tissue with focal lymphocytic infiltration. The patient then underwent lumpectomy, seen here. Otherwise, the patient has a history of Type 1 diabetes mellitus of almost 20-years duration.