Primary Small Lymphocytic Lymphoma of the breast is a rare presentation of Non-Hodgkin's lymphoma. In this report, we present the case of primary small lymphocytic lymphoma of the breast in a 65-year-old female who presented with an abnormal breast ultrasound significant for a nodule of the right breast consistent with BI-RADS 4, indicating follow-up with ultrasound-guided biopsy for further diagnostic evaluation. The patient had no prior history of extramammary lymphoma or widespread disease. A sample of the breast mass was obtained via ultrasound-guided core needle biopsy and the pathology report revealed low-grade B-cell Lymphoma. After discussion with medical oncology and the explanation of risks, benefits and alternatives to surgery, a lumpectomy was performed, and the final pathology report of the mass revealed primary low-grade B-cell lymphocytic lymphoma of the breast. On follow up, the PET scan was unremarkable and showed no evidence of abnormal glucose metabolism or adenopathy.