Variations in lung lymphatic drainage into the inferior tracheobronchial lymph nodes junction: Applications in lung cancer.

The group of inferior tracheobronchial lymph nodes (ITB) is a lymphatic junction through which the lymph from both lungs is carried. Lymphatic activity in this area can be used to assess the lymphatic spreading of lung cancers. Our aim was to quantify lymph drainage from the lung segments towards the ITB group and to determine the direction of the lymph flow into other mediastinal and abdominal lymph nodes. We injected dye directly into the subpleural lymphatic vessels in 100 lung segments of 25 fresh cadaver subjects; the cadavers were then dissected. Thirty-eight segments (38%) drained into the ITB group in 18 subjects. The drainage into the ITB group involved 15.6% of the upper lobe segments, 87.5% of the middle lobe segments, and 70.6% of the lower lobe segments in the right lung. On the left, 6.9% of the upper lobe segments and 83.3% of the lower lobe segments were drained into the ITB group. For three subjects, the dye did not pass beyond the ITB group. The efferent vessels of the ITB group drained towards the right paratracheal and tracheoesophageal chains in 12 subjects and through the left ascending recurrent chain in five subjects. For six subjects, the efferent channels reached the abdominal lymph nodes. A contralateral drainage involved 14 segments (36%). The size and variety of the segments that drain into the ITB group, coupled with the efferent contralateral mediastinal and abdominal pathways, account for the severity of metastasis to this area. Clin. Anat. 29:955-962, 2016. © 2016 Wiley Periodicals, Inc.