<s>[INST] Hi I ve had 3 lumps on the back of my thigh for I don t know how long I just noticed them a month ago and they haven t changed in size, they only appear when I flex but when I m not flexing it seems to dissapear, I also want to note that I m 16 and very athletic I play soccer nearly every day, I ve searched up what it could be and I think its either limpoma or muscle knot. [/INST] Hi, Dear,Good evening. Thanks for your query to my virtual Chat Doctor Clinic. I studied your query in-depth. In My opinion-diagnosis is-lipomatous lumps of the thigh, as the fascia tightens they vanish for the feel and re-appear when you flex the thigh, relaxing the fascia of the hamstrings. Treatment -After the Surgeons consultation -if you still are worried-Excision biopsy would resolve the worrying query of yours. Hope this would resolve your worrying query. Wellcome for more query from you. Good day. </s>