BackgroundWhile the optimal management of early breast cancer patients with sentinel lymph node (SLN) involvement mapped in the internal thoracic chain is still debated, biopsy may be performed when surgeons select patients who are most likely to benefit.The aim of this study is to examine anatomical aspects of internal thoracic nodes (ITNs) to orientate SLN biopsy in the parasternal area.MethodsThis study was based on dissections of 29 female cadavers. The parameters analyzed were the number of intercostal spaces (ICSs) containing at least one ITN, mean number of nodes in each ICS, position of the ITNs in relation to the internal thoracic artery (ITA), number of retrocostal spaces (RCSs) containing at least one ITN, and mean number of nodes in each RCS.ResultsThe ICS that was most likely to have at least one ITN was the third, with 86.2 % in the right side and 75.8 % in the left side. In the second ICS, the rates were 69.2 and 73.6 %, and in the fourth, the rates were 48.1 and 33.3 %. In the third ICS, on both sides, the mean number of ITNs was the highest (1.2). A tendency of the nodes to be laterally located in the second ICS and medially located in the downward dissection was observed. Most of the RCSs did not present any nodes.ConclusionsThis study indicates that most of the second and third ICSs presented at least one ITN, and the mean number of nodes in the third space was greater. There is a tendency to find nodes medial to the artery downwards from the second to the fourth ICS. ITNs are generally located in ICSs, and the majority of RCSs did not contain any nodes.