Lymph nodes associated in regional spread of non-small cell lung cancer metastases — topography, imaging and invasive diagnostic methods

Abstract

Each group of hilar and mediastinal lymph nodes was defined because of specific clinical needs in terms of non-small cell lung cancer lymphatic spread patterns. This classification varies from the one found in anatomy textbooks. The most up-to-date classification was presented by the Association for the Study of Lung Cancer and it describes fourteen separate groups of nodes, in which lymph node groups 1, 2, 4, 8–14 are paired (i.e. right and left sided). Each group has its own characteristics. Most lung tissue is drained throughout subpleural lymphatic vessels to eventually meet in hilar nodes of groups 10 and 11, which are said to be most often the prime station for lung cancer metastases. Next, the lymph runs to mediastinal lymph nodes. This phenomenon has its consequences in TNM classification of lung cancer. In this article we describe detailed topographical features of each lymph node group, present normal and alternative pathways for the lymph drainage, and explain all unexpected clinical observations in the spread of lymphatic metastases. In addition the role of computed tomography and usefulness of positron emission tomography in assessing the nodes is discussed. Finally, we present diagnostic methods, with mediastinoscopy as the best, and we acknowledge the widespread use of the less-invasive endoscopic methods.