My son who is 22 months old has a lump on his left leg just above the knee and behind . We have been observing this from past 4 days. Got ultrasound n blood tests done. No infection in the blood. The infrasound report says "A multilobulated ill marinated non tender hypo-anchors lesion with internal echoes and apparent peripheral soft tissue showing minimal vascular is noted in along subcutaneous plane or left inferior -posterior thigh abutting the underlying muscular facia measuring 4.2*1.6*2.6cm. Mild surrounding subcutaneous edema is noted. Underlying muscles, visualized vessels, bony vortices appear normal. Could you please tell us what is the problem.