Short article structure

It is widely accepted that the malignant infiltration of axillary lymph nodes, follows a stepwise pattern from level I to level II, to level III (infraclavicular), to supraclavicular fossa and or internal jugular chain.

The skip metastases refer to the uncommon phenomenon in which level I is not affected but level II and/or level III are involved. This has been reported to happen in 1.3% to 14.6% of patients in some series.^1-6

In a study of 539 cases treated with total axillary dissection, Veronesi et al, stated that the predictive value of the first level is considerable; when lymph nodes at level one are negative, the probability that infiltrating nodes are present at the second and third levels is minimal. When the nodes at the first level are positive, the chances that metastases are also present at the higher levels are of the order of 40%. ¹

So, in the ultrasound evaluation of the axilla, is safe to stop the scanning when the first level is free of disease; and if it is abnormal, you can go for the infraclavicular level instead of level II, because the eighth edition AJCC staging manual, considers level I and II together. Stage IIIC includes positive lymph nodes in the infraclavicular fossa (level III), or internal mammary chain plus axilla, or supraclavicular nodes, thus cannot be missed in the evaluation. ^7,8

As good practice, you can examine the neck in addition to level III if the infraclavicular nodes are suspicious. ⁷