Location of the Left Hilar Lymph Node
The left hilar lymph node is located in the left hilum of the lung, specifically classified as stations 10 and 11 in the International Association for the Study of Lung Cancer (IASLC) lymph node map, positioned around the left main bronchus and its branches, adjacent to the left pulmonary artery and its divisions. 1
Anatomical Definition and Classification
The hilar zone encompasses lymph node stations 10 and 11, which are part of the N1 nodal classification in lung cancer staging 1. Specifically:
- Station 10: Hilar lymph nodes located immediately adjacent to the main bronchus and hilar vessels 1
- Station 11: Interlobar lymph nodes positioned between the lobar bronchi 1
N1 classification includes ipsilateral peribronchial, hilar, or intra-pulmonary lymph nodes, distinguishing these from the more centrally located mediastinal (N2) nodes 1.
Specific Anatomical Relationships
On the left side, hilar lymph nodes are found in several key locations 2:
- Lateral to the apical segmental artery (A2) - present in approximately 49% of normal individuals 2
- Medial to the interlobar pulmonary artery - consistently present in 100% of cases 2
- Medial to the lower-lobe pulmonary artery - present in approximately 60% of cases 2
- In the angles of bifurcation of the segmental arteries (A7+8 and A9+10) - present in approximately 40% of cases 2
Imaging Characteristics
Normal hilar lymph nodes on spiral CT appear as triangular or linear hypoattenuated areas less than 3 mm wide, except around the left lower-lobe pulmonary artery where they may be slightly larger 2. The left hilum is anatomically complex and can be challenging to image on conventional chest radiography 3.
Clinical Significance
The hilar zone is distinct from mediastinal lymph node stations, which has critical staging implications 1. Involvement of hilar nodes (N1) carries a significantly better prognosis than mediastinal node involvement (N2), with 5-year survival of 48% for single-zone N1 involvement versus 34% for single-zone N2 involvement 1.