Are there any kind of palpable lumps that cannot be picked up on ultrasound? specifically in the upper axillary areas?

Palpable lump/Axilla: Lumps in the axilla which are palpable should be easily picked up on imaging studies like Ultrasound and CT scans. If ultrasound does not pick up a lump, then a CT scan of the Chest should be done and the axillary lump/s should be easily picked up, if it is present. In this regard CT scan is a more reliable test and can 100% confirm if the lump is real or or not.