A case of occult contralateral breast cancer incidentally detected by contrast-enhanced MRI; report of a case with review of literature

We encountered a case of occult contralateral breast cancer, previously undetected by conventional imaging such as mammography (MMG) and ultrasonography (US), but incidentally detected by contrast-enhanced magnetic resonance imaging (CE-MRI). We present it here with a review of the literature. A 67-year-old Japanese woman was referred to our hospital in October 2000 because of a 1.5 cm right breast lump detected in a medical checkup. MMG, US and fine needle aspiration cytology revealed a cancerous lesion during the right breast. No mass lesion was palpable nor was any detected by MMG or US in the left breast. Bilateral breast CE-MRI was performed for more detailed evaluation. Consequently, an occult contralateral breast cancerous lesion was detected incidentally by CE-MRI, with the images showing rapid initial enhancement of time to signal intensity curves. Before surgery, bilateral breast lesions were diagnosed as invasive ductal carcinoma by open biopsy. She underwent bilateral breast conserving surgery with bilateral axillary lymph node dissection. The postoperative course was uneventful and no recurrence has been noted as of January 18th, 2004. CE-MRI of the contralateral breast should be of value as a routine screen in those patients with a known or suspected malignancy in one breast considering the limits of breast cancer detection by such conventional modalities as MMG and US.