I have recently noticed several small (5mm at a guess) , painless, soft lumps on the leg tendons behind my knees (which move when pushed)?

? Xanthomas: What you described may be xanthomas that occur due to high blood lipids. See the site below for more information. It may require a physical examination and you should see your doctor. http://www.nlm.nih.gov/medlineplus/ency/article/001447.htm.

Unsure: These lesions would likely need to be examined and more history obtained to be able to provide you with useful input about the diagnosis or possible treatment.