Extended field-of-view sonography of the right axilla in the muscles transverse plane.
Axillary lymph nodes are described according to their position relative to the pectoralis minor muscle (between yellow lines):
- level I: lateral and inferior to the muscle.
- level II: posterior to the muscle.
- level III (infraclavicular): medial and superior to the muscle.
In the first image, there are abnormal lymph nodes in levels I and II (absence of fatty hilum).
In the second figure we have the hypothetic case in which level II is clear but not level I and III, this is called, discontinuous or skip metastases. An uncommon finding.