<s>[INST] I have a knot that has formed on the outside of both of my legs just under the knee area. It feels like a bruise and the skin over the area I red. I first noticed this about 2 days ago. It protrudes when I bend my knee but isn't that noticeable when standing. What could this be? [/INST] Hello,Thank you for using healthcaremagic.I read your question and understood your concern.This might be inflammation of the knee joints producing more water (effusion) inside the knee that gives that picture.You need to do proper blood tests and imaging studies ( Xray , MRI) to find the right cause.I wish you quick recovery.Dr. Selmani </s>