This case reports on secondary extramedullary multiple myeloma within both breasts in the absence of axillary nodal involvement and discusses the difficulty in interpretation with clinical recommendations and learning outcomes. Differentiating plasmacytic lesions in the breast is often difficult as clinical and radiological appearances are known to mimic benignity and high-grade primary breast cancer. Extramedullary presentation can determine progression of the disease and can necessitate cross-sectional imaging. Therefore definitive diagnosis is essential as the clinical management of the patient may be altered.