Internal mammary lymphadenopathy: imaging of a vital lymphatic pathway in breast cancer

The prognostic significance of metastases to the internal mammary lymph nodes in patients with breast carcinoma has long been recognized. While ipsilateral dissection of axillary nodes remains a popular staging strategy for breast cancer, surgical sampling of the upper anterior intercostal spaces, a tedious procedure, has been largely abandoned. Diagnostic imaging of the parasternal lymphatic pathway is a useful and noninvasive alternative to surgical staging. This report reviews the pertinent regional anatomy and illustrates the criteria for diagnosing internal mammary lymphadenopathy by means of lateral chest radiography, computed tomography, high-resolution sonography, magnetic resonance imaging, and radionuclide lymphoscintigraphy.