Metastasis to regional lymph nodes is of major importance in determining treatment and ultimately survival. Regional lymph nodes are classified as follows. N0=no lymph node metastasis; N1=metastasis to lymph nodes in the peribronchial or the ipsilateral hilar region or both, including direct extension; N2=metastasis to ipsilateral mediastinal lymph nodes and subcarinal lymph nodes, and N3=metastasis to contralateral mediastinal lymph nodes, contralateral hilar lymph nodes, ipsilateral or contralateral scalene or supraclavicular lymph nodes. 

Lymph Node Map

Fourteen numbered nodal stations are illustrated in the diagrams below. N2 nodes are numbered 1 through 9. Ipsilateral nodes are designated right or left (depending on location of primary tumor), midline prevascular and retrotracheal lymph nodes are considered ipsilateral.

Click the lymph nodes in the following diagrams:

Lymphatic Pathway of Lymph Node Spread

Buy et al defined the usual lymphatic pathways of tumor spread into the mediastinum. Abnormal mediastinal nodes were those in the lymphatic drainage territory >10 mm and the difference between this node and the largest node in the other territories was >5 mm. They reduced the number of false positives as compared to methods that used size criterion alone. [Sensitivity 78%, Specificity 99% n=97]

Buy JN, Ghossain MA, Poirson F, et al. Computed tomography of mediastinal lymph nodes in nonsmall cell lung cancer. A new approach based on the lymphatic pathway of tumor spread. J Comput Assist Tomogr 1988; 12:545-552.

This scheme can be examined in the diagram below (modified from Buy).

Axial Lymph Node Map