i have a golfball-sized lump on/in my hamstring half way between knee and hip.  Next to it is a depression in the same muscle.  The mass seems to be involved in the hamstring muscle itself.  I did injure something a few weeks ago which causes deep aching inside the buttock where the muscle attaches to the hip bone structure.
Hi, Golf-ball sized lump on hamstring, midway between hip and knee with a nearby depression after an injury can be due to one of the following reasons:- Hematoma formation-Abscess or cellulitis- Preexisting lump like a lipoma or so. This can be diagnosed by the following ways: Clinical examination by a General Surgeon gives fairly correct diagnosis. To be confirmed by high resolution ultrasonography or MRI as is needed. FNAC that is fine needle aspiration may be needed in selected cases. All these will give a proper diagnosis and a plan of an appropriate management either surgical or medical as the need be. Hope I have answered your query. Let me know if I can assist you further.