1 2 4 5 7 8 9 10 12 13 14 15 1 Fig. 1. left right 15  16 17 2 18 19 Fig. 2. Schematic diagram of the relationship between the lymph capillaries, precollectors, and lymph collecting vessels.  20 21 22 24 This study addresses the lymphatic anatomy of the breast and anterior upper torso. Our findings may explain the clinical experience in lymphatic mapping and sentinel node biopsy, and also the persistence of a false-negative rate of 5–10% irrespective of the experience of the surgeon. Materials And Methods Bilateral anterior upper torso specimens, which included both breasts, were harvested from 10 cadavers (4 male and 6 female) with incisions across the root of the neck, down the posterior axillary line and across the abdominal wall, just above the umbilicus. Another four unilateral studies were obtained from separate cadavers (1 male and 3 females) by a midline incision of the sternum, thus resulting in a total of 24 sides. Protocol refinements at the beginning of the study limited early results and there were always time limits to complete the work, especially on the contralateral side of bilateral subjects, before the specimen became putrefied. The injection and dissection for each side of a specimen took 4–5 weeks. The specimens were stored at −20°C prior to dissection and at 4°C during the dissection. 20 21 3 4 The procedure was performed: around the entire periphery of the specimens in the subcutaneous plane; around the internal thoracic artery on the inner aspect of the chest; and in the vicinity of the perforating branches of the internal thoracic artery to identify superficial lymphatics, internal mammary lymphatics, and perforating lymphatics respectively. Indocyanine Green dye (Pulsion Co., Germany) was injected into the internal mammary artery to demonstrate the artery and its perforating branches, which supply blood to the medial aspect of the breast, thus facilitating the identification of associated deep perforating lymphatics. 22 The specimen was radiographed after completion of all injections to give the two-dimensional views of the lymph vessel anatomy. To provide the three-dimensional views, the female specimens were sliced parallel to the lymph vessels as they passed towards the axilla. These slices were then placed on their sides and radiographed to show the position of the lymphatic collectors with respect to the skin and the breast tissue. Radiographs were photographed (Nikon D100, Nikon Co., Japan) and transferred to the computer, then each lymphatic collector was traced (Adobe Photoshop CS, Adobe System Inc.) to its first-tier node and color coded. All collectors draining to the same first-tier node were assigned the same color after tracing them retrogradely from the sentinel nodes. Results Superficial Lymphatic System 3 4 4 Fig. 3. left right  Fig. 4. Tracing distally of lymphatics of both hemi upper torsos (male: A and C, female: B and D) from each first-tier lymph node colour coded; pectoral node (green, orange, black and yellow), subclavicular node (light blue), and internal mammary node (red). Note (i) that the lymph collecting vessels from the nipple and areolar region on each specimen drain into the green-colored lymph node; (ii) the similar pattern of chest and breast drainage between the male and female studies; (iii) that the breast lies in the pathway of collecting lymphatics that start peripherally and (iv) that, although the majority of the breast drains to one sentinel node in D, every breast area is drained by more than one first-tier node in each study.  5 4 Fig. 5. Photograph of dissection in the areolar region after injecting the mixture of dye and hydrogen peroxide into the nipple. Lymph capillaries and precollectors (black arrows), and lymph collecting vessels (white arrow) were stained with the blue dye.  6 Fig. 6. above below  Internal Mammary Lymphatic System 7 Fig. 7. orange green  superficial perforating superficial Discussion 25 15 1 13 14 26 27 8 28 Fig. 8. 26  198 29 30 Our current anatomical knowledge of the breast lymphatics still depends on Sappey and Poierer and Cuneo’s diagrams. Since Sappey used thin adult cadavers and Poirer and Cuneo used infant cadavers, the relationship between the superficial lymphatics and the adult breast tissue, and also the relationship of the lymphatic drainage of the breast tissue with that of the surrounding superficial tissues, has not been adequately described. Controversy still exists over the role of the subareolar plexus in the lymphatic drainage of the breast. There has been no concrete evidence of a centripetal anatomical lymphatic pathway that drains the breast tissue towards the subareolar plexus and then, via this plexus, towards the sentinel node. Our direct injection technique, however, gives a comprehensive image of the lymphatic system in individual specimens. Each lymph vessel that enters a lymph node can be traced retrogradely to provide an accurate map of the tissue for which that lymph node is “sentinel.” We have photographed, radiographed, and recorded actual lymphatic pathways. In addition, cross-sectional studies have been performed to obtain three-dimensional images of these lymph collecting vessels. We have shown that some of the torso vessels pass from the periphery through the breast tissue on their way towards the axilla. This is discordant with the conventional understanding that they run just underneath the skin. 31 29 30 32 33 4 34 37 technical The surgeons’ experience with the technique or The size of the radioactive tracer which may not reach the lymph node, especially if sited in a peritumoral position. anatomical 9 38 42 43 44 10 12 Fig. 9. Our concept of the breast lymph drainage, drained by both the perforating lymphatic system and the conventional horizontal superficial lymphatic system with their relationship to the lymphatic system beneath the deep fascia.  Conclusions Current anatomical knowledge of the breast lymphatics is derived from the work of Sappey, Poirier, and Cuneo. Our anatomical cadaver study of the relationship of the lymphatics of the torso and the adult breast goes a step further and provides additional information which has special significance for sentinel lymph node biopsy. We have used a refined protocol to accurately record the anterior upper torso lymphatics in adult male and female cadavers. The patterns of the superficial lymphatics were no different between sexes and frequently more than one sentinel node drained the breast. The cross-sectional studies of the female breast showed some lymph vessels of the torso coursing through the breast tissue. We found also perforating lymphatics coursing with similar branches of the internal mammary artery and vein. This anatomical analysis suggests that (i) peritumoral injection is preferable for identification of the sentinel lymph node for breast cancer treatment and (ii) may help explain the incidence of negative sentinel node studies where only the subareolar plexus is injected with the radioisotope tracer.