Breast metastases from extramammary malignancies: multimodality imaging aspects.

Breast metastases from extramammary cancers are rare and usually related to poor prognosis. The extramammary tumours most frequently exhibiting breast metastases are melanoma, lymphomas, ovarian cancer, lung and neuroendocrine tumours, and sarcomas. Owing to the lack of reliable and specific clinical or radiological signs for the diagnosis of breast metastases, a combination of techniques is needed to differentiate these lesions from primary breast carcinoma or even benign breast lesions. Multiple imaging methods may be used to evaluate these patients, including mammography, ultrasound, MRI, CT and positron emission tomography CT. Clinical and imaging manifestations are varied, depend on the form of dissemination of the disease and may mimic primary benign and malignant breast lesions. Haematologically disseminated metastases often develop as a circumscribed mass, whereas lymphatic dissemination often presents as diffuse breast oedema and skin thickening. Unlike primary carcinomas, breast metastases generally do not have spiculated margins, skin or nipple retraction. Microlobulated or indistinct margins may be present in some cases. Although calcifications are not frequently present in metastatic lesions, they occur more commonly in patients with ovarian cancer. Although rare, secondary malignant neoplasms should be considered in the differential diagnosis of breast lesions, in the appropriate clinical setting. Knowledge of the most common imaging features can help to provide the correct diagnosis and adequate therapeutic planning.