Internal mammary lymphoscintigraphy in breast cancer

Abstract

The parasternal chain of lymph nodes is a significant drainage area from the breast. The involvement of these lymph nodes with metastatic breast disease is associated with a poor prognosis. Multiple reports on the physiology and pathology of the parasternal nodes are available in the literature (1,3,4,6,8X The classical textbooks of anatomy contain a concise description of the lymphatics associated with the internal mammary vessels as seen in cadaver. The parasternal lymph nodes are placed at the anterior ends of the intercostal spaces, beside the internal mammary vessels. They are variable in number, and most of them are in the upper chain. They derive afferents from the mammary gland, from the deeper structures of the anterior abdominal wall above the umbilicus, from the upper surface of the liver, to a small group of nodes which lie behind the xiphoid process, and from the deeper parts of the anterior portion of the thoracic wall. Their efferents usually unite to form a single trunk on either side. They may open directly into the junction of the internal jugular and subclavian veins, alternately, that of the right side may join in the right subclavian trunk and that of the left the thoracic duct. Perforating lymphatics in the upper intercostal spaces constitute lymphatic communication between the axillary and the internal mammary pathways. Visualization of the parasternal lymph nodes by scanning following the injection of colloidal gold ls8 is a well-established procedure. Its application as a clinical test for detection of internal mammary lymph node metastasis has been the subject of only a few publications ($7). In both presentations, the normal anatomical patterns of these lymph nodes were evaluated. The Kazem et al (5) evaluation identified four main patterns of parasternal lymph nodes as seen on the scan. All four patterns were normal anatomical variations. Pattern one was characterized by two parallel chains of nodes on either side of the midline behind the sternum. Pattern two was characterized by two parallel chains of nodes on either side behind the sternum, but the nodes are grouped in the upper five intercostal spaces. These two patterns constitute 85 percent of the patterns seen in the populations examined. Pattern three identified parasternal nodes arranged in one midline single channel inferiorly located posterior to the sternum. This single channel then bifurcates into two separate channels on each side of the sternum, opposite the third or second intercostal space (,‘Y shaped’ pattern). Pattern four was seen the least frequently; it was characterized by the presence of one solitary chain which may be centrally located behind the sternum or located laterally on either side of the sternum. The Ege data (2) represents a study of 1,072 patients. It makes a major contribution since the data are comparable to the results of surgical excision and histological examination of the internal mammary nodes. Unlike surgical extirpation, the technique is simple, can be repeated, and provides a significant, noninvasive means for individual patient assessment. The data also indicate that Tcssm antimony colloid, with a particle size of four to eleven millimicrons, has provided scintographic images within three hours after the injection, that are of diagnostic quality and similar in character to those obtained from gold*S*. The data derived from the parasternal lymphoscintigraphy were utilized to relate the incidence of parasternal involvement with stage of breast