Breast carcinoma is the leading cause of cancer death in women. Metastatic tumours of the oral cavity arising from breast cancer (and other forms of cancer) may be similar to hyperplastic or reactive lesions. They are uncommon and typically appear when various organs have already been affected by the neoplasia. A 53-Year-old woman presented with "discomfort" in her left mandible, specifically, swelling of recent onset accompanied by progressive loss of sensation. The mandibular swelling had been preceded by neuralgia involving the trigeminal nerve. Biopsy and histologic examination of the intrabony mass revealed ductal adenocarcinoma with infiltration of bone and stromal tissues. The lesion was determined to be metastatic from previously undiagnosed breast cancer. The neuralgia was also related to a metastatic lesion.