Lymph node axillary metastasis from occult contralateral infiltrating lobular carcinoma arising in accessory breast: MRI diagnosis.

We describe a case of right axillary lymph node metastasis of an occult infiltrating lobular carcinoma arising from accessory mammary gland of the left upper anterior chest wall. Ultrasonography and mammography were normal bilaterally. Magnetic resonance imaging (MRI) revealed a 3.34 cm inhomogeneous lesion. Then, core biopsy under ultrasound guidance demonstrated a typical infiltrating breast lobular carcinoma. To our knowledge, this is the first case reported in the literature of an axillary lymph node metastasis from an occult contralateral infiltrating lobular carcinoma of the accessory breast tissue. MRI was useful for assessing the lesion of the accessory breast tissue.