Figure 5.

False positive. 38 year old female with invasive ductal carcinoma of the left breast with metastases to left axillary lymph nodes. Breast magnetic resonance imaging was performed prior to neoadjuvant chemotherapy. There is loss of fat plane on T2 sequences (a), and no enhancement of the pectoralis muscle (arrow) on post contrast sequences (b). Diffusion weighted imaging was interpreted as positive for pectoralis muscle invasion based on consensus read. After neoadjuvant chemotherapy, final surgical pathology did not show evidence of skeletal muscle involvement.