The lymphatic map of the lung-subdivision of N2 non-small cell lung carcinomas

Background. The prognosis of resected N2 diseases (ipsilateral mediastinum node metastasis) in non-small cell carcinoma of the lung is heterogeneous and difficult to predict. To precisely assess the prognosis of N2 diseases, we made a lymphatic map of each pulmonary lobe and subdivided the current N2 diseases. Methods. We mapped the lymphatic pathways of each pulmonary lobe and classified these lymphatic pathways as follows: level 1: from the lung to the intra-pulmonary or hilar nodes (N1); level 2: from N1 to the ipsilateral mediastinum nodes (N2); and level 3: among N2 nodes. We assessed 585 computed tomography (CT) studies of patients with a primary complex of histoplasmosis, which included the association of single, well-defined, calcified lung nodules and hilar and/or mediastinum calcified lymph nodes. And we made the lymphatic map of the each pulmonary lobes. Results. The lymphatic map disclosed the lymphatic pathways specific for each lobe. The common skip mediastinal station was specific in each lobe: the right lower paratracheal node in the right upper lobe, the subaortic node in the left upper lobe, the pulmonary ligament, and paraesophageal node in the bilateral lower lobes. Skip N2 metastases are uncommon in the right middle lobe. The mediastinum stations involved were as follows: the most commonly involved station was the lower paratracheal node in the right upper lobe, the subcarinal node in the right middle lobe, the subcarinal node in the right lower lobe, the subaortic node in the left upper lobe, and the pulmonary ligament node in the left lower lobe. Conclusions. We classified the current N2 findings into three stages: minimal, early, and advanced N2 disease progression, depending on which level of the lymphatic system is mainly contributing to nodal involvement.