Hi, thanks for sharing your son s health concerns with HCM! If I were his treating Doctor for this case of the movable lump/tightness in the upper thigh, I would come up with three possibilities, these include: 1. a lipoma or benign fatty tumor or neurofibroma 2. The second possibility is of a benign cyst like ganglion cyst bursa 3. The last possibility is of a lymph node or even could be some normal / developmental nodule like muscular nodule or just kind of muscular sprain! Overall, it is benign and not to worry about this but you could go for FNAC test for confirmation before consulting a surgeon in your area! He might have rest and continue physiotherapy as you mentioned.... Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing your son good health.