Felt lump in left armpit. doc says he feels no lump but based on tenderness it is inflamed. he is sending me for ultrasound. what would cause this?

Blocked sweat gland: The most common reason is a blocked sweat gland. They can become painful but can usually be easily treated. The ultrasound is to see if the area has a collection of fluid that can be drained. A good idea. If so, draining is a good idea. If no fluid, then usually start antibiotic to treat probable infection in the blocked duct. Hope this helps. Good luck!

Many possibilities : Your physician has ordered an ultrasound to help make a diagnosis. The fact that you felt a lump and have tenderness needs to be explained. It is possible to have cysts that come and go. Swelling and inflammation of sweat glands, blood vessels, hair follicles and muscular tissue are all possible. Tumors are less likely but need to be ruled out. An ultrasound with follow up is appropriate. Relax.